diff --git a/modules/gltf/doc_classes/GLTFDocumentExtension.xml b/modules/gltf/doc_classes/GLTFDocumentExtension.xml
index abdbce7eeb..b217955edc 100644
--- a/modules/gltf/doc_classes/GLTFDocumentExtension.xml
+++ b/modules/gltf/doc_classes/GLTFDocumentExtension.xml
@@ -6,7 +6,7 @@
 	<description>
 		Extends the functionality of the [GLTFDocument] class by allowing you to run arbitrary code at various stages of glTF import or export.
 		To use, make a new class extending GLTFDocumentExtension, override any methods you need, make an instance of your class, and register it using [method GLTFDocument.register_gltf_document_extension].
-		[b]Note:[/b] Like GLTFDocument itself, all GLTFDocumentExtension classes must be stateless in order to function properly. If you need to store data, use the [code]set_additional_data[/code] and [code]get_additional_data[/code] methods in [GLTFState] or [GLTFNode].
+		[b]Note:[/b] All GLTFDocumentExtension classes are duplicated when beginning the import or export process. Except for configuration values, these classes must be stateless in order to function properly. If you need to store data, use the [code]set_additional_data[/code] and [code]get_additional_data[/code] methods in [GLTFState] or [GLTFNode].
 	</description>
 	<tutorials>
 		<link title="Runtime file loading and saving">$DOCS_URL/tutorials/io/runtime_file_loading_and_saving.html</link>
diff --git a/modules/gltf/gltf_document.cpp b/modules/gltf/gltf_document.cpp
index 1bda104af6..52c2ab846a 100644
--- a/modules/gltf/gltf_document.cpp
+++ b/modules/gltf/gltf_document.cpp
@@ -6552,9 +6552,13 @@ Error GLTFDocument::_parse(Ref<GLTFState> p_state, const String &p_path, Ref<Fil
 	document_extensions.clear();
 	for (Ref<GLTFDocumentExtension> ext : all_document_extensions) {
 		ERR_CONTINUE(ext.is_null());
-		err = ext->import_preflight(p_state, p_state->json["extensionsUsed"]);
+		Ref<GLTFDocumentExtension> ext_dup = ext;
+		if (ClassDB::is_class_exposed(ext->get_class_name())) {
+			ext_dup = ext->duplicate();
+		}
+		err = ext_dup->import_preflight(p_state, p_state->json["extensionsUsed"]);
 		if (err == OK) {
-			document_extensions.push_back(ext);
+			document_extensions.push_back(ext_dup);
 		}
 	}
 
@@ -7118,9 +7122,13 @@ Error GLTFDocument::append_from_scene(Node *p_node, Ref<GLTFState> p_state, uint
 	document_extensions.clear();
 	for (Ref<GLTFDocumentExtension> ext : all_document_extensions) {
 		ERR_CONTINUE(ext.is_null());
-		Error err = ext->export_preflight(state, p_node);
+		Ref<GLTFDocumentExtension> ext_dup = ext;
+		if (ClassDB::is_class_exposed(ext->get_class_name())) {
+			ext_dup = ext->duplicate();
+		}
+		Error err = ext_dup->export_preflight(state, p_node);
 		if (err == OK) {
-			document_extensions.push_back(ext);
+			document_extensions.push_back(ext_dup);
 		}
 	}
 	// Add the root node(s) and their descendants to the state.