I have 7 diffrent cory species in one tank and they all get along fine.i think most if not all cories get along with each other, they are very pieceful. they like to be in groups of their own species, but i think 3 is a resonable number.
Just make sure the water parameter is similar so it won't compromise too much. Personally I strongly believe that Panda is happier in cooler temperature than most people keep them. Although I don't know the best parameter for Pepper. Hopefully cooler side.