Hmmm... Ive gone in manually and tried searched every face, edge and vertex thourougly, but I I have not been able to find the duplicated edge.. Ive tried moving a lot of them around to see if theres a face or vertex hidden under another etc, but without luck.

Any other ways of finding this/these edge(s) ?

This is a part of the message I get -

"Repair the duplicate edges by selecting the polygon
// and issuing the following command, then try again:
select .e[1423] .e[1422] .e[1421] .e[1420] .e[1419] .e[1418] .e[1417] .e[1416] .e[1415] .e[1414] ;string $v[] = `polyListComponentConversion -fe -tv`;select $v;polySplitVertex;polyMergeVertex -d 0.0


Those numbers - are they some form of codes I can use to find the duplicated edges?