Why would they need to be separate? The law regulates the magazine. The magazine must be incapable of feeding more than X rounds continuously. A set of attached magazines cannot feed more than 10 rounds into any given action in this setup with 10 round mags attached to each other.
I have a Pelican 1700 case that I accidentally knocked down a flight of stairs in my hotel (don’t ask, I was fumbling around), my rifle didn’t even lose zero.
Even after many, many trips being beaten up by airline baggage handlers, not once, has it failed me.
I’ll trust Pelican.