RuntimeError: boxlists should have same image size, got BoxList(num_boxes=1, image_width=640, image_height=53 7, mode=xyxy), BoxList(num_boxes=9, image_width=537, image_height=640, mode=xyxy)

[khieu]

I am training rcnn with the multi-gpu scripts but got the following error:
RuntimeError: boxlists should have same image size, got BoxList(num_boxes=1, image_width=640, image_height=53 7, mode=xyxy), BoxList(num_boxes=9, image_width=537, image_height=640, mode=xyxy)

This error does not happen when training with single GPU model. Does anyone know how what the cause of this issue is and how to resolve it?

Thank you in advance.