Ran across this issue with a server I was connecting to that wouldn't accept ^? as the backspace in vim which is what made me finally notice the error. Turns out both of my LMDE installs bind backspace as ^? instead of ^H and refuse to let you override it to ^H. Sounds like a patch that was sent out a few years ago which freebsd removed but may have snuck its way into the LMDE project. The freebsd bug report: http://www.freebsd.org/cgi/query-pr.cgi?pr=153942
I have no idea if that is the culprit but I thought maybe someone with more skill might be able to confirm that or not. I just know both installs that bash has ^H, screen has ^H, and tmux has ^?. One was made months ago and the other was done this week.