Left shift and alt are stuck together My left shift and left alt seem to be stuck together, as in when I press one the system acts as both were pressed (the keyboard viewer shows both pressed as well).

It only happens with the built-in keyboard on my Macbook (Mid 2012 edition, with OS X 10.10.5).

This started today and I've restarted, and also reset the NVRAM, but no luck so far. Any suggestions?
Probably a hardware problem rather than a software problem. Take it to the Apple Store and they'll check the underneath of the keyboard.