When you have a degree in Herpetology, have logged 10 years as a curator of animals at a zoological institution and or have about 100 years experience like Jack....then by all means, have at it.
If you are a newbie and have joined a forum a few months ago and don't even have 2 different species worth of experience under your belt....
If you have to ask about mixing....that says it all right there.
Please don't manufacture excuses with bad analogies......