Would it be a bad idea to introduce lab rats to my current rats?

[Lisa]

I was wondering if it would be a bad idea to introduce lab rats to my current rats. I am a new rat owner and have had problems with two of my rats having respiratory infections. One cured very quickly and easily and I haven't had problems but the new one, I recently discovered, has a respiratory issue. I was watching him very closely after I got him and at first he was only making a weird breathing noise late at night and only one "fit" of it for a few seconds so I took him to the vet. I'm treating now is having an issue with recovery. He has been on meds for almost a week and was showing signs of improvement but then started to fall back and started to get red mucus on his nose. I do not use bedding but do use a litter box. I use "yesterdays news: unscented" but it says it is for cats but my other ratties have not had any breathing issues and they even sit in the litter box sometimes. They have new hammocks that I cleaned with dish detergent instead of regular store detergent because I figured the sell wouldn't be good for them. He has a vet appt tomorrow to see whats going on. He is in the same room with my other rats in a separate cage but he was with his also when he begun to make the strange noise and they seem to be doing just fine. I'm guessing he's having a Myco flare up since the other did not show the same signs. But HERE'S my question, since I know Mycoplasma pulmonis is seen in pretty much all rats except lab rats, would it be a bad idea to give these two ex-lab guys a home when I know they will probably end up getting Mycoplasma pulmonis? Or would it be a selfish, cruel thing to do?