Fixed a bug with materials in PSK export

io_scene_psk_psa/psk/export/operators.py

@@ -29,7 +29,7 @@ def populate_material_list(mesh_objects, material_list):
             if material is None:
                 message = bpy.app.translations.pgettext_iface('Material slot cannot be empty (index {index})')
                 raise RuntimeError(message.format(index=i))
-            if material.name not in materials:
+            if material not in materials:
                 materials.append(material)
                 
     for index, material in enumerate(materials):