You said..."Can i house 2 veiled chameleons together in the same cage.They would be a male and a female."...they can be housed together from birth to about 3 months of age then they need to be separated. If you keep two together in the same cage after that you will eventually end up with a pregnant (gravid) female that hasn't even had time to finish growing her own bones but now has to use calcium for eggs. The stress on the two of them will eventually kill one of them anyway. Even two females won't do well if they share a cage.
You said..."Also would they know when to stop mating or would i have to seperate them after a certain amount of clutches"...the female will tell the male that she is gravid by her coloration. Some males will pay attention to that message and leave the female alone....some won't. Even if the male does "listen", the stress levels for both of them will go up. The female will constantly be trying to avoid the male and vice versa.
If you are going to have a female, you need to provide a place for her in her cage to start to dig in case she needs to lay eggs. The signs that they are wanting to lay eggs are often subtle and can be missed by newbies. If she has no place to lay the eggs she will become eggbound and die.
Here are some sites that you might like to read..
http://adcham.com/
http://www.chameleonnews.com/
http://web.archive.org/web/20060502074401/www.chameleonjournals.com/vet/index.php?show=5.Vitamin.A.html
http://www.uvguide.co.uk/skintests.htm#discussion