When you say from behind, I believe you mean your anus. You are a woman, you can make one man lie on the bed on his back and you sitting on him while facing him and he entering in your vagina, while the other man can penetrate his penis from behind in your anus or he can even try to enter your vagina at the same time if you are ready to bear a little pain.
The answer is, yes, it is possible, but it can be quite painful. If you don't mind the pain, then do proceed slowly and with caution as you do not want to tear the muscles of the rectum. It should be ok to do it occasionally, but doing it too often can stretch the sphincter muscle too much and cause inconsistency or lack of control.
You don't want to get to a situation that are unable to hold your stools and it just falls out. Also make sure that both the penetrators use condoms. Both men can enter your vagina at the same time but in the anus is little impossible because of the position of the anus.
The problem would be how those 2 men would position themselves to penetrate your anus, it seems very difficult and little impossible too. And if somehow you manage to get 2 penises in your anus then there's possibility that you might tear your anus and it could be dangerous.
If you really want 2 penis to enter your anus then first try with 2 dildos and then try for 2 penis.