Thanks for looking, Eli. You're right, they are different. For some
yet-unknown reason I was seeing those lines break my M-backspace
binding. Restarting with 'emacs -Q' made it work, even with those lines
enabled.
Regardless, I do think the patch is appropriate. Suppose a user has
customized those particular keys in their .emacs to have some particular
global binding. Why would it be desirable to override those
customizations for VHDL?