I think that in your case a better idea can be to use one data loader but with different data sources. If you write it well you will still be able to control batch_size and images size.
However if you still need to use your idea, maybe better option is use one loop:
for item1, item2 in zip(dataloader1, dataloader2):
    image_batch1, labels1 = item1
    image_batch2, labels2 = item2

If it does not help you, please describe your problem with more detail.