Thanks for all your help.
Just to clear things up and be consistent the following points allied to this bug could be addressed:
1/ during a single point match when gnubg loses by a gammon it pops up a message saying I have won TWO points
2/ similarly gnubg will resign from a single point match offering me a gammon and then pop up a message saying I have won TWO points
Clearly, as you have both pointed out there is only ever one point at stake in such a match.Robert
From: Christian Anthon
That you can double here is a bug. And if you are playing 1 point
matches and the program incorrectly allows you to double it would
explain your observervations.