This thread must remain about packaging and not get off topic or it will be closed. I would encourage the OP to start a thread in vendor feedback if he/she feels the need to do so.
Everytime I have shipped corals I sandwich the coral base/frag plug between 2 pieces of styrofoam so that the frag is floating in the bag and then I triple bag them, never had a problem that way, I would NEVER EVER EVER ship corals 2 to a bag