Ok, I found out what was going on with mine. Somehow keyboard layouts were accidentally enabled ( probably by me ).
This feature (AFAICT) is enabled to insert characters with accents and other key encodings ( encodings is probably an incorrect term in this case , what is the correct term ? ) that are used in foreign language support. Anyway, the keys that were affected when these were ON ( keyboard layouts ) were only the quote , doublequote ( double quote ), apostrophe, caret (fang uparrow hat ^ ), and back tick ` . Evidentally the tilde would have given the same grief, but I didn't check that.
The ( what I thought was aberrant erroneous ) keyboard behavior experienced was I would press one of the aforementioned key once and nothing would happen, press it twice and I'd get the key pressed.
After I found the info on the web, I tried the intended use, and it worked fine (these nux programmers are amazing).
I wound press back tick Shift a (cap A) end I'd get one with back-tick-on-top-of-a-cap-a. A page found makes ref to
" dumpkeys | grep compose " (without the double quotes)
that gave an indication of how my keyboard would react.
Control Center > Regional & Accessibility > Keyboard Layout > Enable keyboard layouts .. was on .. turned em off by unchecking da checkbox.