Just for closure ...
I had a little hunt for these cables once Dougie had pointed this one out to me; saw a splitter with Pimoroni (who I normally use for Pi-related stuff) but wasn't too happy with the longer cable lengths & having a pair of Micro USBs dangling around. So went for the PiHut version, as it's a hellovalot neater !
Arrived this morning, and works a dream
Very happy not to have two cables sticking out & about any more
If only I could do similar with a set of 5 across to a small breadboard I use on this Pi !
So - Dougie, many thanks for pointing me to this