Double tapping j in insert mode exits insert mode

Question

I've managed to break my vim such that if I double tap j in insert mode then it exits insert mode without typing either of the js. I've done a full restart and no joy follows.

What have I managed to do?

Answer 1

Figured it out thanks to Kent.

:iunmap jj
:iunmap kk

No idea how they magically got mapped to all of a sudden (vimrc says nothing).

It's entirely possible that I've just not noticed this behaviour before... I've been using it for a good 4-5 years though :(