This just happened.
I pinned an image and made a new board for it. While I was doing that, a board called "Adorbs" (which appears to be a communal board) showed up on my list of boards and the pin was going to load on that. I again typed the title for my new board, uploaded pin. Clicked to view it and the board had another pin...
I reported it but could not delete it.
WOW, a whole lotta spamming going on.
I then tried pinning the item again in a new virgin board. This time there were TWO other pins.
I changed my password and deleted the two bad boards.
The "Adorbs" board does not appear publicly, but it's still polluting my upload list. I don't know how to get rid of it.
I put in a complaint to Pinterest Support, hopefully they can remedy the situation.
I feel violated. (I know, strong word for stupid Pinterest. First world problem. Still...)