Contact can "not exist" if you do not want it to. Yes, usually by being with one man at a time. Or you can arrange to give one oral sex while having intercourse with the other in such a way that they don't touch. It isn't that difficult.
The issue of sperm though is one you'll have to think through. If you are going "bare back" as we always did, one man is going to have to fearlessly go where another man has gone before. It was not big deal in our case. For some reason that almost didn't seem like "contact" to the guys as long as they were just touching each other's sperm with their cocks. But there was no way either of them were going to intentionally touch the others ejaculate in any other way if they didn't have to. When it was inside of my pussy they just plunged in and used it as lubricant. They seemed quite happy to do so.
I think they just wanted to get laid badly enough that they enjoyed seeing the other with me and the residue of my first guy was coincidental to the next one.