Keyboard Typing Double Letters After an Update? Read This First
Quick answer: If your keyboard suddenly types double letters, it is either a worn switch that is "chattering" or a software setting — often a key-repeat delay or a driver that changed after a Windows update. Confirm which by watching a single deliberate press register twice on the keyboard test.
Software first, because updates change things
After a feature update, it is worth ruling out software before opening anything. A too-short key repeat delay makes held keys double, and you can lengthen it in Control Panel, Keyboard. A reinstalled or generic keyboard driver can also misbehave — reinstalling it from Device Manager is a quick test. Filter Keys can mask rapid repeats as a temporary measure while you investigate.
When it is genuine switch chatter
On a mechanical keyboard, a worn or dirty switch bounces and registers twice. Compressed air and a little electronic contact cleaner around the affected switch cure many cases for free. If the same key keeps doubling, the switch is worn — on a hot-swappable board you can drop in a new one in seconds, which is exactly why hot-swap and the newer magnetic switches have become popular. Magnetic Hall effect switches sidestep chatter entirely because they have no physical contact to wear.
Isolate the culprit key
Chatter is per-switch, so usually just one key doubles while the rest are fine. The keyboard test reads raw key events, so pressing the suspect key once and seeing two registrations is clear proof it is hardware, not your typing. Our full guide on a keyboard typing double letters walks through cleaning, settings and replacement.