Hello ! An easy workaround is to create two dataloaders, one for eatch dataset.
a, b = torch.ones(100,5,5), torch.zeros(100,4,4)
dla = torch.utils.data.DataLoader(a, batch_size=2)
dlb = torch.utils.data.DataLoader(b, batch_size=2)
for i,j in zip(dla,dlb):
    print(i,j)