When you viewing your coins on “My coins” page and you filter coins by “For swap only” (example page link for my user ID https://en.numista.com/vous/vos_pieces.php?user=39128&ct=coin&issuer=russia&type=&comp=All&swap=2&grade=&date=&comm=)
Near each item you have “Delete” button. When you click on it and in case you have same coin in your collection, but not for swap, then that coin displayed instead of deleted coin from the swap list and that coin once again have “Delete” button near it. That creates a case when you have a list filtered by “For swap only”, but at the same time you have coins from your collection in the list. That way I have deleted few coins from my collection by mistake.
