I broke a folder of messages into folders of first and last half of years.
Copied by sent date, Jul 1 to Dec 31, from the old pst currently not set as
the download from server one into the active pst with appropriately named
subfolder. It involved near 10K messages, or at least that is the result to
the new folder. Of roughly 2K of messages it made 2 copies. Read ones
received and unread copy as well as original messages unread.

I've seen this behavior before and it isn't fun going through and deleting
long lists of interleaved duplicates. Sometimes it is probably a mess up on
my ISP's server, or least the possibility existed. This time that was
impossible.
If anyone knows the reason for duplicates maybe I can avoid it in the
future. ???

Unfortunately I deleted the messages from the original store so I can't just
empty the new folder and try it again. I did run a scanpst on this store,
just don't remember if that was before or after I attempted the copy. Maybe
I have a quicker fix than deleting a couple of thousand, maybe I don't.

Norman