well, to me it's like anything else... if you are prepared to loose one to the other, without notice, then house them together. if that thought is completely unthinkable... then house them apart. ultimately it is your decision.

personally i've had 4 dragons in total. just having them around each other... in the house and getting along perfectly and then all of a sudden a quick dash and one is beating the crap out of the other... i can't imagine what would have happened had i not been right there to break them up (okay my hubby broke them up - but still)...

so honestly, i would never house two together regardless of sex.