Neal, when a mommy spider loves a daddy spider.......
....never mind. Perhaps at a later date I'll explain why having a male and a female OF THE SAME SPECIES in the same general area (even if it is just for a short time) is actually a very smart idea.
The above pictures serve as primes examples of sexual dimorphism. All the species pictured above are very well known in the hobby, Haplopelma lividum, Poecilotheria metallica, and Poecilotheria ornata, so I'm a bit surprised by the comment. While the females are known to be brightly colored, the males turn a dull color upon their ultimate (mature) molt. To get more spiders I put the males in with the females. They do their thing, and then the males are removed. He then gets another week to "recharge" and then I place him with another female. Kind of like this:
And now the above male will produce another sperm web and pair with another female early next week.
Call me crazy, but I think it was a very smart idea to have them together. Though I think the outcome I anticipate is different from that which you hinted toward above.
If the above examples of dimorphism look amazing, check out my other posts or my FB pictures. Some of the males are 1/2 to 1/3 the size of the girls. Those are scary pairings but the little guys get the job done.