Rats often pee on each other, I guess as a show of dominance or just because they are buddies and they want to mark them. Male rats do this especially, but even females will do so on occasion.
Here is Roofy peeing on Tommy’s back:
I’ve even seen some male Norway rats pee in their own hammock. Not just to mark them, but apparently because they just didn’t feel like getting out of bed to pee at that moment. You can imagine that sleeping in pee doesn’t leave one smelling very good.
Anyway, rat food with Yucca is supposed to help control urine odor. Oxbow Essentials Regal Adult Rat food has Yucca extract to reduce urine odor. So, if the problem is due to them peeing on each other (or themselves) then at least the pee will be less smelly.
Finally, a high protein diet produces urine with more Nitrogen in it, which will have a stronger odor due to Urea breaking down to ammonia. Adult male Norway rats should be on a lower protein diet anyway, because they will otherwise tend to gain weight as they get older. Overweight rats are more sedentary and likely to pee in their hammocks. They are also generally more unkempt as they will have more trouble reaching all the spots that need cleaning.
So, you should make sure you are feeding adult male Norway rats not more than 16% protein rat food and consider switching to 15-14% protein rat food and see if that helps a bit. Oxbow Essentials Regal Adult Rat food has 15% protein so it is a very good choice.