OK, just incase you get two males in a tank, i know this is a NO NO, but just in case, if you get them from they are babies. How old before the4y start fighting?
Well I have a 5 month old male that thinks he is ready to even breed, so you can bet he would fight if there were another male close enough to him.
I wouldn't recommend housing any geckos together until you are 100% sure of the sex. Not to mention the added benefits the individual gecko gets by being housing by itself at least until it is able to be sexed.
I was told the same thing about crested geckos, males will fight, end of story. However, i have two males together, i got them together when they were a month old, they are now 13 months old, have been sexually mature for a very long time and never fight. They never even made an attempt to fight. I always expected it and everyday i am prepared to separate them if need be, but so far so good! I dont own any females and that may have something to do with it. I do not recommend this though to anyone, as i said before everyday i am prepared to separate them. I think its a rare case and probably the exception not the rule. 9 out of 10 times two males will fight, so its not a good idea to even attempt it.