I finally found some time to address this problem. It is indeed related to the fact that the new number gets assigned when you click on 'New'.
So if two people edit the new entries at the same time, they get assigned the same number. To fix this problem, I made the tag generation work with the
'Subst' command, which is evaluated at the entry submission, and not when you click on 'New'. So to make this work, you need to upgrade |