Not sure about what is going on, it has been reported here Both me and original reporter are using KDE. I have installed Gnome and the problem seem to have gone away.

Additional info:
If I type "A", the result is "AA".

This problem extends in whole interface (dialog preferences, system comboboxes,...)

Steps to Reproduce:
1. Enter de program
2. Type anything everywhere

Actual Results:
duplicates the keyboard inputs

Expected Results:
doesn't duplicate the keyboard inputs
Reproducible: Always
User Profile Reset: Yes
OpenGL enabled: Yes

Did anyone else experience this?