diff --git a/src/adapters/tgk_store_fs/tgk_store_fs.c b/src/adapters/tgk_store_fs/tgk_store_fs.c
index 8be7897..09543b0 100644
--- a/src/adapters/tgk_store_fs/tgk_store_fs.c
+++ b/src/adapters/tgk_store_fs/tgk_store_fs.c
@@ -6,6 +6,56 @@
 #include <stdlib.h>
 #include <string.h>
 
+static bool amduat_tgk_store_fs_id_space_valid(
+    amduat_tgk_id_space_config_t id_space) {
+  size_t i;
+  size_t j;
+
+  if (id_space.domains_len != 0 && id_space.domains == NULL) {
+    return false;
+  }
+  for (i = 0; i < id_space.domains_len; ++i) {
+    for (j = i + 1; j < id_space.domains_len; ++j) {
+      if (id_space.domains[i].hash_id == id_space.domains[j].hash_id) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+static bool amduat_tgk_store_fs_artifact_eq(amduat_artifact_t a,
+                                            amduat_artifact_t b) {
+  if ((a.bytes.len != 0 && a.bytes.data == NULL) ||
+      (b.bytes.len != 0 && b.bytes.data == NULL)) {
+    return false;
+  }
+  return amduat_artifact_eq(a, b);
+}
+
+static bool amduat_tgk_store_fs_reference_clone(amduat_reference_t src,
+                                                amduat_reference_t *dst) {
+  uint8_t *digest_copy;
+
+  if (dst == NULL) {
+    return false;
+  }
+  *dst = amduat_reference(src.hash_id, amduat_octets(NULL, 0));
+  if (src.digest.len == 0) {
+    return true;
+  }
+  if (src.digest.data == NULL) {
+    return false;
+  }
+  digest_copy = (uint8_t *)malloc(src.digest.len);
+  if (digest_copy == NULL) {
+    return false;
+  }
+  memcpy(digest_copy, src.digest.data, src.digest.len);
+  dst->digest = amduat_octets(digest_copy, src.digest.len);
+  return true;
+}
+
 static void amduat_tgk_store_fs_reference_free(amduat_reference_t *ref) {
   if (ref == NULL) {
     return;
@@ -166,6 +216,7 @@ bool amduat_tgk_store_fs_init(amduat_tgk_store_fs_t *fs,
   amduat_reference_t *refs = NULL;
   size_t refs_len = 0;
   amduat_tgk_store_mem_artifact_t *artifacts = NULL;
+  size_t artifacts_len = 0;
   size_t i;
 
   if (fs == NULL || manifest_path == NULL || asl_store == NULL) {
@@ -173,6 +224,10 @@ bool amduat_tgk_store_fs_init(amduat_tgk_store_fs_t *fs,
   }
   memset(fs, 0, sizeof(*fs));
 
+  if (!amduat_tgk_store_fs_id_space_valid(config.id_space)) {
+    return false;
+  }
+
   if (!amduat_tgk_store_fs_load_manifest(manifest_path,
                                          manifest_format,
                                          &refs,
@@ -191,23 +246,49 @@ bool amduat_tgk_store_fs_init(amduat_tgk_store_fs_t *fs,
 
   for (i = 0; i < refs_len; ++i) {
     amduat_asl_store_error_t err;
-    artifacts[i].ref = refs[i];
-    artifacts[i].artifact = amduat_artifact(amduat_octets(NULL, 0));
-    err = amduat_asl_store_get(asl_store, refs[i], &artifacts[i].artifact);
+    amduat_artifact_t artifact = amduat_artifact(amduat_octets(NULL, 0));
+    bool duplicate = false;
+    bool conflict = false;
+    size_t j;
+
+    err = amduat_asl_store_get(asl_store, refs[i], &artifact);
     if (err != AMDUAT_ASL_STORE_OK) {
-      size_t j;
-      for (j = 0; j < i; ++j) {
-        amduat_tgk_store_fs_artifact_bytes_free(&artifacts[j]);
-      }
-      amduat_asl_ref_list_free(refs, refs_len);
-      free(artifacts);
-      return false;
+      goto cleanup;
     }
+
+    for (j = 0; j < artifacts_len; ++j) {
+      if (!amduat_reference_eq(artifacts[j].ref, refs[i])) {
+        continue;
+      }
+      duplicate = true;
+      if (!amduat_tgk_store_fs_artifact_eq(artifacts[j].artifact, artifact)) {
+        conflict = true;
+      }
+      break;
+    }
+
+    if (conflict) {
+      free((void *)artifact.bytes.data);
+      goto cleanup;
+    }
+    if (duplicate) {
+      free((void *)artifact.bytes.data);
+      continue;
+    }
+
+    if (!amduat_tgk_store_fs_reference_clone(refs[i],
+                                             &artifacts[artifacts_len].ref)) {
+      free((void *)artifact.bytes.data);
+      goto cleanup;
+    }
+    artifacts[artifacts_len].artifact = artifact;
+    artifacts_len++;
   }
 
-  free(refs);
+  amduat_asl_ref_list_free(refs, refs_len);
+  refs = NULL;
   fs->artifacts = artifacts;
-  fs->artifacts_len = refs_len;
+  fs->artifacts_len = artifacts_len;
 
   if (!amduat_tgk_store_mem_init(&fs->mem, config, fs->artifacts,
                                  fs->artifacts_len)) {
@@ -215,6 +296,16 @@ bool amduat_tgk_store_fs_init(amduat_tgk_store_fs_t *fs,
     return false;
   }
   return true;
+
+cleanup:
+  if (refs != NULL) {
+    amduat_asl_ref_list_free(refs, refs_len);
+  }
+  for (i = 0; i < artifacts_len; ++i) {
+    amduat_tgk_store_fs_artifact_full_free(&artifacts[i]);
+  }
+  free(artifacts);
+  return false;
 }
 
 bool amduat_tgk_store_fs_init_with_asl_fs(
diff --git a/tests/tgk/test_tgk_store_fs.c b/tests/tgk/test_tgk_store_fs.c
index d9fd81a..3d571f0 100644
--- a/tests/tgk/test_tgk_store_fs.c
+++ b/tests/tgk/test_tgk_store_fs.c
@@ -387,6 +387,225 @@ cleanup:
   return exit_code;
 }
 
-int main(void) {
-  return test_manifest_load();
+static int test_init_rejects_duplicate_hash_id(void) {
+  amduat_asl_store_config_t asl_config;
+  amduat_asl_store_fs_t asl_fs;
+  amduat_asl_store_t asl_store;
+  amduat_tgk_store_config_t tgk_config;
+  amduat_tgk_store_fs_t fs;
+  amduat_tgk_identity_domain_t domains[2];
+  char *root = NULL;
+  char *manifest_path = NULL;
+  int exit_code = 1;
+
+  memset(&tgk_config, 0, sizeof(tgk_config));
+  memset(&fs, 0, sizeof(fs));
+
+  root = make_temp_root();
+  if (root == NULL) {
+    fprintf(stderr, "dup hash temp root failed\n");
+    goto cleanup;
+  }
+  if (!join_path(root, "manifest.txt", &manifest_path)) {
+    fprintf(stderr, "dup hash manifest path failed\n");
+    goto cleanup;
+  }
+  if (!write_manifest(manifest_path, NULL, 0)) {
+    fprintf(stderr, "dup hash manifest write failed\n");
+    goto cleanup;
+  }
+
+  asl_config.encoding_profile_id = AMDUAT_ENC_ASL1_CORE_V1;
+  asl_config.hash_id = AMDUAT_HASH_ASL1_ID_SHA256;
+  if (!amduat_asl_store_fs_init(&asl_fs, asl_config, root)) {
+    fprintf(stderr, "dup hash asl store fs init failed\n");
+    goto cleanup;
+  }
+  amduat_asl_store_init(&asl_store, asl_config, amduat_asl_store_fs_ops(),
+                        &asl_fs);
+
+  domains[0].encoding_profile = AMDUAT_ENC_ASL1_CORE_V1;
+  domains[0].hash_id = AMDUAT_HASH_ASL1_ID_SHA256;
+  domains[1].encoding_profile = AMDUAT_ENC_ASL1_CORE_V1;
+  domains[1].hash_id = AMDUAT_HASH_ASL1_ID_SHA256;
+
+  tgk_config.id_space.domains = domains;
+  tgk_config.id_space.domains_len = 2;
+
+  if (amduat_tgk_store_fs_init(&fs, tgk_config, manifest_path,
+                               AMDUAT_FORMAT_REF_HEX, &asl_store)) {
+    fprintf(stderr, "dup hash init accepted\n");
+    amduat_tgk_store_fs_free(&fs);
+    goto cleanup;
+  }
+
+  exit_code = 0;
+
+cleanup:
+  free(manifest_path);
+  if (root != NULL) {
+    remove_tree(root);
+  }
+  free(root);
+  return exit_code;
+}
+
+static int test_manifest_duplicate_refs(void) {
+  amduat_asl_store_config_t asl_config;
+  amduat_asl_store_fs_t asl_fs;
+  amduat_asl_store_t asl_store;
+  amduat_tgk_store_config_t tgk_config;
+  amduat_tgk_store_t store;
+  amduat_tgk_store_fs_t fs;
+  amduat_tgk_identity_domain_t domains[1];
+  uint32_t edge_tags[1];
+  amduat_tgk_edge_type_id_t edge_types[1];
+  amduat_asl_encoding_profile_id_t encodings[1];
+  amduat_octets_t edge_bytes;
+  amduat_reference_t ref_edge;
+  amduat_reference_t node_a;
+  amduat_reference_t node_b;
+  amduat_reference_t payload;
+  uint8_t digest_node_a[32];
+  uint8_t digest_node_b[32];
+  uint8_t digest_payload[32];
+  amduat_tgk_graph_scan_result_t scan;
+  amduat_tgk_edge_body_t body;
+  amduat_tgk_edge_body_t edge;
+  amduat_reference_t edge_from[1];
+  amduat_reference_t edge_to[1];
+  char *root = NULL;
+  char *manifest_path = NULL;
+  int exit_code = 1;
+  bool fs_ready = false;
+
+  memset(&tgk_config, 0, sizeof(tgk_config));
+  memset(&fs, 0, sizeof(fs));
+  memset(&body, 0, sizeof(body));
+  edge_bytes = amduat_octets(NULL, 0);
+
+  root = make_temp_root();
+  if (root == NULL) {
+    fprintf(stderr, "dup refs temp root failed\n");
+    goto cleanup;
+  }
+  if (!join_path(root, "manifest.txt", &manifest_path)) {
+    fprintf(stderr, "dup refs manifest path failed\n");
+    goto cleanup;
+  }
+
+  asl_config.encoding_profile_id = AMDUAT_ENC_ASL1_CORE_V1;
+  asl_config.hash_id = AMDUAT_HASH_ASL1_ID_SHA256;
+  if (!amduat_asl_store_fs_init(&asl_fs, asl_config, root)) {
+    fprintf(stderr, "dup refs asl store fs init failed\n");
+    goto cleanup;
+  }
+  amduat_asl_store_init(&asl_store, asl_config, amduat_asl_store_fs_ops(),
+                        &asl_fs);
+
+  domains[0].encoding_profile = AMDUAT_ENC_ASL1_CORE_V1;
+  domains[0].hash_id = AMDUAT_HASH_ASL1_ID_SHA256;
+  edge_tags[0] = TYPE_TAG_TGK1_EDGE_V1;
+  edge_types[0] = 0x10;
+  encodings[0] = TGK1_EDGE_ENC_V1;
+
+  tgk_config.id_space.domains = domains;
+  tgk_config.id_space.domains_len = 1;
+  tgk_config.artifact_scope.description = amduat_octets(NULL, 0);
+  tgk_config.tgk_profiles.edge_tags = edge_tags;
+  tgk_config.tgk_profiles.edge_tags_len = 1;
+  tgk_config.tgk_profiles.edge_types = edge_types;
+  tgk_config.tgk_profiles.edge_types_len = 1;
+  tgk_config.tgk_profiles.encodings = encodings;
+  tgk_config.tgk_profiles.encodings_len = 1;
+
+  node_a = make_ref(0xa1, digest_node_a);
+  node_b = make_ref(0xb1, digest_node_b);
+  payload = make_ref(0xe1, digest_payload);
+
+  memset(&edge, 0, sizeof(edge));
+  edge.type = 0x10;
+  edge_from[0] = node_a;
+  edge.from = edge_from;
+  edge.from_len = 1;
+  edge_to[0] = node_b;
+  edge.to = edge_to;
+  edge.to_len = 1;
+  edge.payload = payload;
+
+  if (!amduat_enc_tgk1_edge_encode_v1(&edge, &edge_bytes)) {
+    fprintf(stderr, "dup refs edge encode failed\n");
+    goto cleanup;
+  }
+
+  if (amduat_asl_store_put(
+          &asl_store,
+          amduat_artifact_with_type(edge_bytes,
+                                    amduat_type_tag(TYPE_TAG_TGK1_EDGE_V1)),
+          &ref_edge) != AMDUAT_ASL_STORE_OK) {
+    fprintf(stderr, "dup refs asl store put failed\n");
+    goto cleanup;
+  }
+
+  {
+    amduat_reference_t refs[2];
+    refs[0] = ref_edge;
+    refs[1] = ref_edge;
+    if (!write_manifest(manifest_path, refs, 2)) {
+      fprintf(stderr, "dup refs manifest write failed\n");
+      goto cleanup;
+    }
+  }
+
+  if (!amduat_tgk_store_fs_init(&fs, tgk_config, manifest_path,
+                                AMDUAT_FORMAT_REF_HEX, &asl_store)) {
+    fprintf(stderr, "dup refs tgk store fs init failed\n");
+    goto cleanup;
+  }
+  fs_ready = true;
+  amduat_tgk_store_init(&store, tgk_config, amduat_tgk_store_fs_ops(), &fs);
+
+  if (amduat_tgk_store_resolve_edge(&store, ref_edge, &body) != 0) {
+    fprintf(stderr, "dup refs resolve_edge failed\n");
+    goto cleanup;
+  }
+  amduat_tgk_edge_body_free(&body);
+  memset(&body, 0, sizeof(body));
+
+  if (!amduat_tgk_store_scan_edges(&store,
+                                   (amduat_tgk_edge_type_filter_t){0},
+                                   amduat_octets(NULL, 0), false, &scan)) {
+    fprintf(stderr, "dup refs scan_edges failed\n");
+    goto cleanup;
+  }
+  if (scan.edges.len != 1) {
+    fprintf(stderr, "dup refs scan_edges count mismatch\n");
+    amduat_tgk_graph_scan_result_free(&scan);
+    goto cleanup;
+  }
+  amduat_tgk_graph_scan_result_free(&scan);
+  exit_code = 0;
+
+cleanup:
+  amduat_tgk_edge_body_free(&body);
+  if (fs_ready) {
+    amduat_tgk_store_fs_free(&fs);
+  }
+  free((void *)edge_bytes.data);
+  free_ref(&ref_edge);
+  free(manifest_path);
+  if (root != NULL) {
+    remove_tree(root);
+  }
+  free(root);
+  return exit_code;
+}
+
+int main(void) {
+  if (test_manifest_load() != 0 ||
+      test_init_rejects_duplicate_hash_id() != 0 ||
+      test_manifest_duplicate_refs() != 0) {
+    return 1;
+  }
+  return 0;
 }