Isn't that strange - I "cooked" 082 (-clones, marked β082 - I think they were by RFT from the then GDR) with the 79xx in a devie I designed while doing PhD. Specifically it was 7909, as I had 40xx multiplexors in the circuit and wanted to get as much voltage swing as possible. Strangely, the positive 7809 died, too, but the 40xx survived (too slow to be bothered by oscillations??).
As a remedy, besides proper decoupling, I added LEDs to each supply rail (there was also 5V for logic and 12V for sensors, ans also some weird negative - like -21V or so - but unstabilized - as an interface to an old machine, driving some bunch of relays) and there were LEDs indicating commuication and status; so the box ended up looking like an accessory from some bad scifi film...

Btw. the 7809 measured by an analog meter (I had no DMM then) 9V all the time, although it was incredibly hot with almost zero load - the result of oscillations.

Jan Waclawek.