Wow... I had no idea that it can take them that long to color. I have a tragic story that might explain why I assume that they are both female. I actually bought a trio of them and a male (in my mind the only male) started to color up. Soon after I moved them into the current tank along with a couple nylons full of gravel from the old tank (was trying to help the bio-spira). I neglected to cut off the excess tail of the nylons and the male kenyi swam into one of them and got stuck and died.
I know that the story was completely unrelated but use this is a warning if you plan on putting nylons full of gravel in your tank... CUT OFF THE TAIL END!!! Fish can be curious!
Anyways... back to the point...
Would I be better off if I removed one of them... I really don't want to get rid of both unless I absolutely have to... I like the contrast between them (striped) and the other three species (all solid colors)... plus I'm sorta attached to them after seeing them grow up and all...