I think any guy that does that is an ass. What's the point? If you want multiple girls, just go for multiple one night stands - at least then you aren't cheating on anyone.
If you're honest with both of them about not being exclusive, and they're happy with that and don't want to be exclusive either - no problem. If you're lying to one or both of them, they'll probably cut your balls off when they find out, and you'll deserve it.
Its really difficult to manage two girlfriends/boyfriends at this point of time as every one knows recession period is going on
If you can manage them and if you are not serious about them or they are not serious about you, no harm in trying.
You are not cool. You will just fail harder. Google will know you had two girlfriends and reduce your PR and Adsense ban you.
I'm personally never did such a thing, and don't think of doing it, just wanted to see how to opinion are splitting between the members here
I used to do that, and like others mentioned I was always honest with them and let them know they were not the only one... I never let them know who the other(s) were, but always let them know they were there. I found it worked so good that there were tiems even when there were not others... I would lie and say there was.. not only to cover myself incase some did come up... but because most of the girls seem to digg it and enjoy the mysticism. Good luck!