that said, recently i started having double keystrokes on some of my keys...
1st on a second hand filco which started having issues... i wanted to desolder all of them but the seller in china i asked to order keycaps from recommended me try trying cleaning the filco with isophropyl alcohol into the switches, and leave it to dry up. that did the trick (i use syringes *(but the needle pokes on the plastic stems, so maybe u can use some old plastic syringe for medication instead )
the other time it was a DZ64 which the solder came off (bad soldering on my second board). resolding it solved that. If u feel like you are starting to have some double entries, just try the alcohol method first, inject to said key, press it a few times, and leave it to try.
on a seperate note, avoid head powered solder sucker. i bought a couple, and they both clog up with a few uses and you need to dismantle to remove the solder inside. go for a non powered solder sucker or solder wick instead.
or use some old wires lying around to use as wick.