hasnt happened yet - i dont think it will occur naturally - could possibly occur if you play god and start intervening with drugs and chemicals etc...
general rule - peppermint b/n wont breed with any other b/n - neither will orange spot b/n...
common , albino , lemon , calico/marble/piebald are all derived from common b/n so they can and will interbreed with each other... short or long finned
