Raise error for duplicate params in param group #40967 (#41597)
Summary:
This PR fixes an issue in https://github.com/pytorch/pytorch/issues/40967 where duplicate parameters across different parameter groups are not allowed, but duplicates inside the same parameter group are accepted. After this PR, both cases are treated equally and raise `ValueError`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/41597
Reviewed By: zou3519
Differential Revision: D22608019
Pulled By: vincentqb
fbshipit-source-id: 6df41dac62b80db042cfefa6e53fb021b49f4399
