Forum,
I am running the code from the VAE-GAN from the INTERSPEECH 2020 paper Voice Conversion Using Speech-to-Speech Neuro-Style Transfer.   This also happens with the UNIT paper code.
Pytorch is giving a warning as follows:
UserWarning: optimizer contains a parameter group with duplicate parameters; in future, this will cause an error; see Inconsistent behaviour when parameter appears multiple times in parameter list · Issue #40967 · pytorch/pytorch · GitHub for more information
The problem is with the shared block and it appears that this is going to be error moving forward yet I’m unsure how to fix the issue so I van continue using pytorch for these types of structures.  If it is going to error out I will need an understanding how to get this to work.
The block is shared:
shared_dim = opt.dim * 2 ** opt.n_downsample

Initialize generator and discriminator
encoder = Encoder(dim=opt.dim, in_channels=opt.channels, n_downsample=opt.n_downsample)
shared_G = ResidualBlock(features=shared_dim)
G1 = Generator(dim=opt.dim, out_channels=opt.channels, n_upsample=opt.n_downsample, shared_block=shared_G)
G2 = Generator(dim=opt.dim, out_channels=opt.channels, n_upsample=opt.n_downsample, shared_block=shared_G)
D1 = Discriminator(input_shape)
D2 = Discriminator(input_shape)
The warning is occurring when the Adam optimizer is being defined:

Optimizers
optimizer_G = torch.optim.Adam(
itertools.chain(encoder.parameters(), G1.parameters(), G2.parameters()),
lr=opt.lr,
optimizer_G, lr_lambda=LambdaLR(opt.n_epochs, opt.epoch, opt.decay_epoch).step
betas=(opt.b1, opt.b2),
)
optimizer_D1 = torch.optim.Adam(D1.parameters(), lr=opt.lr, betas=(opt.b1, opt.b2))
optimizer_D2 = torch.optim.Adam(D2.parameters(), lr=opt.lr, betas=(opt.b1, opt.b2))

Learning rate update schedulers
lr_scheduler_G = torch.optim.lr_scheduler.LambdaLR(
optimizer_G, lr_lambda=LambdaLR(opt.n_epochs, opt.epoch, opt.decay_epoch).step
The G1 parameters and G2.parameters have a shared block of weights and this I believe is causing the issue.  Duplicate parameters? I haven’t been able to find any remedy to this issue, yet the sharing of blocks does occur in many of the newer papers.
Any suggestions on how to get around this warning?
Bests,
Philip