Add raw args then validate for duplicate flags

lib/render_workers/blender_worker.py

@@ -61,6 +61,11 @@ class BlenderRenderWorker(BaseRenderWorker):
         # all frames or single
         cmd.extend(['-a'] if self.render_all_frames else ['-f', str(self.frame_to_render)])
 
+        # Convert raw args from string if available
+        raw_args = self.get_raw_args()
+        if raw_args:
+            cmd.extend(raw_args)
+
         return cmd
 
     def _parse_stdout(self, line):