@Wolfgang thank you for the response but the “remains a mystery to me!!” was me misunderstanding the problem that @John-M had reported, i.e. I had successfully recreated it but failed to recognise the fact that the error/warning message was identical as was the outcome if I selected “yes”.
So I had successfully recreated the problem with my test, but failed to recognise that fact and made an erroneous comment!
That is actually the first time I have seen that particular error but have seen the first scenario I documented where two exports run one after the other and the second attempts to make duplicate copies and is failed by DxPL has happened to me in the past.
But no-one else recognised that the DxPL response was identical in both cases, except that @John-M appears to be using an Olympus camera and I am using a Panasonic, ORF versus RW2!
@Joanna got the issue spotted as two exports in one run where I tested two exports in one run but in @Joanna’s case it was two export options being selected at the same time and my test was two separate exports started in close succession which happened to clash!!
So I owe @Joanna an apology for my misunderstanding when your words were plenty clear enough although I did realise part way through my testing and added the correct test!