I have had it working before but I can't seem to get things right this time.

I want to have two different copies of debian on one box with the
choice of which when I boot in.
Wanting to have available both debian stable (9.5 at present) and
debian testing (10). This is so I can experiment with software - - -
adding it and if huge errors result or are caused - - - no real biggie
because its not a main working box (like the server or my main
computer). Doing this because I really have gotten to hate having a
main box down for even a few days because software that I loaded and
installed caused me to bork the system (I've done this more than a few
times!!! grin - - -but 'learning' isn't always a barrel of fun!!)

So I've installed both of these systems (more than once each) they
have their own partitions for everything but boot and efi yet I'm only
seeing one system available on grub (depending upon the last install
as to which). So I'm doing something wrong!! I tried using grub
updating tools (# os-prober) still no joy. The web pages that I'm
finding seem to be for an older version of grub and, as usual, I'm
finding man pages are like reading cuneiform (which I find

This is likely something quite simple but I'm just not seeing it - - -
please - - - some ideas/pointers?