Inspection on Saturday, 2- 50- gallon water heaters, 4-&5 years old, the cold water supply line on the newer water heater was getting hot as I ran the hot water. the water was hot, and both water heaters fired up. I ma thinking the dip tube is damaged on the one heater.
Were the tanks connected in series or parallel? Whenever you are looking for help with this kind of question, a couple of photos will make it 1000 times easier for someone to help you. Otherwise, they are just guessing, a poor substitute for facts.
I do have a photo , very busy, home owner has a lot of stuff hanging all over the place.