Great Question , it doesn't have to be both coins, personally, I am currently not holding any ZCL but I will still be credited the BTCP on a 1:1 ratio. The thing to remember is to have your coin(s) in a wallet where you control/own the private key or on an exchange that is supporting the fork. I hope this answer helps, cheers.
RE: What the fork is going on!!!!! (Part 2 of 2)