Generally speaking, the best way to keep most cory is keep with many of their own kind. However most would prefer to be with other corys over few corys(1~3). Although one of the problems of keeping many different species cory in the same tank is you have more risk of getting hybrid.
Then again, there are so many similar corys out there unless you are really expert of corys some is almost impossible to tell them apart. So we might be growing hybrid unintentionally sometime.
That is another reason it is a good idea to buy decent group(6 and up) at one time. Of course, the tank have to be mature to handle all the fish you acquire. It is often near impossible to find the same species even if you go back to the same store sometime. Especially some not so common species.
Anyway, the answer to your question is . Yes, they do definately do better with more Corys even they are not same species. But watch out for the hybrid. Also, you do have to make sure their water parameter preference is similar. Also similar size is preferable.
