I figured out a terribly complicated solution:
Deleting all file from the published location, deleting the collection in the publishing service module, re-adding the collection, re-publishing everything. Then, all file are numbered form 1-n.
Can't be the final answer, can it?
You probably shouldn't use an export service to do this as it resets the file number every time you do a republish. Just a simple export will do it just fine. From looking around the web this appears to be a general problem with how the publish services work and it appears impossible to avoid duplicate numbering.
Hello Jao vdL,
thanks for your reply. Probably your hint to just use the simple export is the best approach.
Reordering or renaming already published photos may be a complicated problem to solve. However, it seems like a bug to me that numbering is not reset even after I say republish all photos.
I'm disappointed by Lightroom here. It could do better.