congrats to sprocket on his manhood . just a little fyi--both males and females have spurs--similarly to ball pythons. sometimes males have slightly larger spurs but it isn't always noticeably so.

the only time i house males together is if they are clutchmates and have been housed together since birth. once they reach between 6-9 months i separate them to avoid any fighting or other male dominance issues. some people have had success housing males together in large enclosures with lots of hiding places and adequate space for each gecko. i haven't tried it myself, but wouldn't say it can't or shouldn't be done since some have had success with it.

like christie said, if you put a female in with a male you will get eggs. if you want eggs then go for it, but make sure that you get a female of adequate size and age (minimum of 35 grams and 1 year old) and that she and your male are similar in size.

any time you house cresteds together they should be of similar size. a larger crested will dominate a smaller crested which will stress it and cause it not to grow and possibly become sickly. this isn't anything that the larger gecko does on purpose, but being larger it will get food faster and get more of it, it will always get the "good" hiding spot or the preferred branch or whatever, and the smaller one will suffer because of it.