Well, not all frogs in the same population look the same. Some population may not have a huge diversity, but some might. Justin Y. has picture floating around of a group of basti pumilio all from caught on the same tree. I believe it had 5 frogs that looked different enough, that if you didn't have local data they would be separated into different morphs. If you only breed frogs that look the same you are going to breed the natural diversity out of them.
This is why local data would be very nice to have, but we don't a lot of the time. The basti pumilio, doesn't matter if it's red, orange, or yellow could be paired up with each other without creating a hybrid or mixed dart. That is why it is so important to know the history behind the blood line of your darts.
Now most morphs, be it auratus, tincs, or whatever are generally labeled into different locals. So you would not want to breed these, because you are mixing the blood lines.
Now if you want a tank with 5 different tincs, nobody (well almost nobody) will want to tar and feather you as long as you don't raise any eggs. You can keep them together. You have to watch out for behavioral issues also when you are mixing dart species in a tank too. In another thread, there is a tank that has live 4-5 different species all from the tinc group: see link for groups
(Dart Groups). Frogs in the same group can cross and create hybrid offspring, so all eggs need to be tossed from tanks that have frogs mixed from with in the same group. I have seen pictures of frogs that have been crossed and it is very hard if the froglets are pure or not. Example Tinc (morph A) keep in tank with Tinc (morph B) produce offspring that look like morph A, morph B, and morph C (mixed). That is why people are so concerned about people keeping a mixed tank. Toss the eggs, and if you get to the point you want to breed them, pull a same morph pair and give them a new tank by themselves.
These are my feelings and not the view of DendroBoard. This is a touchy issue and just want to make it clear this is how I feel, and how I believe many froggers feel.
Hope this helps,