I 've tested both dataloaders and they are still not synchronized correctly; again, I use
next(iter(..)), as in
img_batch1 = next(iter(dataloader_1))  
img_batch2 = next(iter(dataloader_2))

I am still getting different images in img_batch1 than in img_batch2
Note. I had to set the number of workers to zero to get it working.
random_seed()
dataloader_1 = DataLoader(test_set1, 
batch_size= 5, 
shuffle=True, 
num_workers=0,
worker_init_fn = torch.initial_seed()
)
random_seed()
dataloader_2 = DataLoader(test_set2, 
batch_size= 5, 
shuffle=True, 
num_workers=0,
worker_init_fn = torch.initial_seed()
)