Ah! well double marking is not supported - and lots of people wish it was.
If anyone is in a position to experiment, then it might be possible to impelement something using a new question behaviour plugin (https://docs.moodle.org/dev/Question_behaviours). The problem you will hit is MDL-69699 - which is something I really need to fix.
If anyone is in a position to experiment, then it might be possible to impelement something using a new question behaviour plugin (https://docs.moodle.org/dev/Question_behaviours). The problem you will hit is MDL-69699 - which is something I really need to fix.