Hi,
Batchnorm actually has some learnable parameters. So if you re-use it, it will share these learnt parameters across the different use.
Also it is saving the running stats to be used in evaluation mode. And so if you re-use it, these stats will be shared.
It might or might not be what you want, depending on your use case.
You can check the doc for the detail on how to use each argument: https://pytorch.org/docs/stable/generated/torch.nn.BatchNorm2d.html#torch.nn.BatchNorm2d 18