I have to double every command? (V 2.76) Recently, my PC crashed after I upgraded from Windows 7 to 10. I was able to restore my PC back to Windows 7, but since then I have had an issue with having to repeat everything within Blender. A perfect example would be with the text tool. If I add a text object that should say "Blender", when I'm done typing as such, I have an end result of "Blende". The same goes for loopcuts. I have to stop one short, or I have one too many. However, and this is the weird part, if I use the screencast keys addon, problem solved. No need to repeat anything, everything is as it should be. I have refreshed defaults, and gone so far as uninstalling and reinstalling Blender. Any ideas?
The loop cut example sounds like normal behavior, so I don't know what you're experiencing. If you could upload a video demonstrating the problem, maybe that could help us diagnose. 

Until then, try refreshing blender with factory defaults. You can do this by removing your user prefs. By default, these are stored in:

Windows 


  C:\Users\%USER%\AppData\Roaming\Blender Foundation\Blender\%VERSION%\config\


Linux


  ~/.config/blender/%VERSION%/config/


Remove or rename config folder and blender should start up with factory defaults. 

A simpler way is to start blender from the terminal (CMD) with the --factory-startup flag to bypass any and all config files (there are multiple locations blender searches for user prefs). 

Windows blender --factory-startup

Linux ./blender --factory-startup