I went through two MBPs with this issue. Yes, you can technically just keep mashing keys over and over until they stick and/or delete the 2+ instances of the character each time it finally types, or you could technically hook up an external keyboard for the laptop, but... both "solutions" are pretty much showstoppers for a laptop. The issue did make my computer unusable and I was unable to work on it.

Side note: I dropped from 110+ WPM to ~20 WPM because I had three keys with this issue and had to spent 5+ seconds every time I tried any of those keys. The worst part is sometimes it wouldn't register the key and sometimes it would register it on the first try but type the character several times repeatedly. It was literally hell.