The problem is the needless duplication of information. It may not be a huge problem in this case, but it is the thin end of the wedge. It's a simple matter of commonly agreed forum etiquette.
I don't think that cross-posting is only to be deprecated when it may cause confusion. It seems particularly pointless to post the same information twice in succession in the same forum - there would be more justification for posting a copy of the message in several different forums here, but that would surely be frowned upon.
The problem is that now we have caused more noise by discussing the matter.