Some old sailors never throw anything out. Certainly not something that just might help save them one day. We will have timexed ELTs that transmit on 121.5 in circulation until that frequency ceases to be valid for distress signals. Sometimes they will go off, though that is usually some half-cut bogan fisherman in his tinny accidentally kicking it or dropping it in his haste to get to the esky. Real yachts have them on a bulkhead bracket (or, once they become illegal, hidden inside a locker and properly secured).
Some of us will keep our old safety gear to supplement the new until the authorities establish a special branch to hunt us down and shoot us on sight for such blatant civil disobedience. Maybe that's a job for a revitalised CASA.......
The authorities also tell us we must dispose of old flares. The reason given is that they become unstable, or unreliable. Which may be true after a very long time. Flares don't suddenly burst into flames a week or even a year after their expiry date, and every old one I ever banged off in training worked just fine. A totally law-abiding mariner may hand them in at each flare replacement date, but a mariner with a less anal outlook would probably keep them as back-up and only chuck them after about three years. Similarly with the old 121.5 beacons - for as long as they test OK they will remain aboard most boats, and I dare say a few aircraft.
New 406 beacons are supposed to be registered. When one goes off, I believe that the usual practice before mounting SAR is to start with the contact number(s) provided on the registration to try and determine whether it is likely to be the real deal or not. Because of that excellent idea, it is quite probable that the authorities don't take 121.5-only signals from unidentified sources as seriously as they once did.
But you can never have too many signalling devices on a boat. Or in an aircraft that has just force-landed in the desert or the jungle.