can i mix lead and rhythm and still have a rhythm guitarist in a band?

What you describe is fairly common.  Trying to duplicate the other guitar part is a waste of time, since it's unlikely to improve the sound and may very well degrade it.  A good strategy is to play sparsely, stay out of the range the rhythm player is centered on, and complement the other player's part.

There's no law against two guitarists playing rhythm at the same time. What you want to be mindful of is not clashing with each other. If you play in *perfect* unison, the rhythm will sound full. If you are sloppy or out of sync with each other, it will sound like doggy doo. It's more common for the two players to either play counterpoint or different inversions of the same chord. For instance, one player could use open chords, and the other play barre chords higher on the neck.

Another option for the lead player is to simply not play(!) when there is no need for a lead. If you simply can't control the need to be playing something, some tasteful accents would work.