in the attached pic i have lots of duplicates. I have used the join command to join these lines.
when i select “seldups” it says “no duplicates found”

why do i still have lots of duplicates? i missing something. i am using WIP

You may have negatively impacted duplicate selection by Joining.

I would explode or otherwise revert back to the pre-joined state and run SelDup then.
Perfect duplicates will be selected to they can be deleted.
Then the meticulous effort of selecting and joining, finding overlaps etc, and you should get what you’re after.

You also might find that using the mess of duplicates and overlapping curves can be manually traced over to make clean curves.

All this is guessing without a small example file.
A screenshot for something like this is all but worthless.

I did as you suggested and ran explode and had 47 dups
now when i try to run the join i have 2 selections, curve and surface. i can see the difference in the line weight, so i am selecting the surfaces 1 by 1 and deleting.
AA175-st1.3dm (328.9 KB)