I kept them together in a 29 gallon tank I had and there wasn't a problem but there was a mix of male and female of both species so that might not be a proper comparison.
I do that a bit on FB... bore all my friends with albums full of fish! LOL
I have a special one also for my guppy born without a proper snout. Didn't know if she'd make it but she has grown nicely and seems to have no other defects.
Breeders would normally cull defective fish like that. Since you are not a breeder you get to see how it turns out and see if the defect reduces its ability to take care of itself which is interesting in and of itself.
I had several females at the time and didn't even notice her lack of a snout for a couple of months.... by then, felt terrible to cull her so when I re-homed most of my little females I kept her. She can't feed from the top of the tank but is doing just fine catching bits that fall, she does a lot of nibbling at stuff on plants and on the bog wood.