Help? Chat character malfunction

Yes, it did it with a new, clean install and no addons at all. Keyboard is a simple, 10 keyless, mechanical one. No frills. /shrug

It’s behaving as if I pressed the key twice, but changing the key binding does not help, so it can’t be some hardware thing on that key. aanndd ii ddoonntt ttyyppee lliikkee tthhiiss…