Hi Wang-zipeng,
Unfortunately, I don’t know faster-rcnn. However, I think that the each copy’s gradient will be updated (and it’s depend on the same loss function). Each copy’s gradient should be the same after updating.
By the way, I suggest you use the nn.ReLU instead of F.ReLU because nn._ can be used to fusing layer during QAT process.
I hope this can be helpful for you. If any question, welcome to discuss with me!