Great that you found a workaround.
Did this happen because there was an interrupted backup at some point?
It looks like the error happens if one of the remote dlist files are already marked for deletion.
When the delete command then tries to mark the dlist files, it only marks the ones that are not already marked, and this causes the error.
But I am not sure how to get into that state in the first place. Can you see the first failed one you have, if there are any hints as to how this could happen?