Am I being wrong to both my Friends with Benefits (FWB)?

It's hard to come across a relationship nowadays so I've downgraded to FWB. I have two FWB's that I hook up with regularly. When one can't put out, I hook up with the other. Quite frankly, I have needs and that's how it goes. I keep in touch with both on a daily basis, but one has a girlfriend and the other is dating someone. The FWB that's dating someone is always asking me if I'm seeing someone because he doesn't want to contract a disease of some sort. I feel if I approach it like a man does by not caring about their emotions and use each other to our advantage, then it's not wrong.