Training is very important in duress systems. I once worked in a place with a keypad duress code on the security system. If you prefixed your security PIN with NN-, it was the duress version of the code and would trigger a silent alarm. This was setup long-ago, and not communicated. One night, the keypad was acting glitchy. Partially out of frustration (countdown is running), and partially to test, I ended up acciden…
I mean it happens, the security company sent out a van already (as they should) and called to confirm. They charge a fee (just over €100 I believe? Or €250? I forgot) for false alarms, but that's fair enough. Better safe than sorry.
Anyway, a DIY store with at most 100K in the safe (weekly takings at the time, most of that was probably electronic) is probably a lot less serious than whatever you were working for, to have it surrounded by law enforcement.