glTF exporter: avoid double export

Make sure to not check instances inside instances collection when GN instance is enable.

scripts/addons_core/io_scene_gltf2/__init__.py

@@ -5,7 +5,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Scurest, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (4, 3, 15),
+    "version": (4, 3, 16),
     'blender': (4, 2, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

scripts/addons_core/io_scene_gltf2/blender/exp/tree.py

@@ -448,7 +448,9 @@ class VExportTree:
                     dupli_world_matrix=mat)
 
         # Geometry Nodes instances
-        if self.export_settings['gltf_gn_mesh'] is True:
+        # Make sure to not check instances for instanced collection, because we
+        # will export what's inside the collection twice
+        if self.export_settings['gltf_gn_mesh'] is True and node.blender_type == VExportNode.OBJECT:
             # Do not force export as empty
             # Because GN graph can have both geometry and instances
             depsgraph = bpy.context.evaluated_depsgraph_get()