Using edge if I go to my eBay and in the drop down select watch list. For each item I am watching when I pull up that listing the option to add to watchlist is visible. Normally once a item is in the watch list this changes to add to list. I clicked add to watch list and a green message came up saying item was added to my watch list. I closed out and checked my watch list there where no doubles in my watch list. I also tried not clicking add to watch list and checked my watch list to make sure the items was still in the list. I also noticed to the left of my eBay there is a new tab for watchlist this pulls up a pop up screen that you can scroll through the watch list. I checked again and got the same results as earlier.
Clearly eBay ran some update to add the new tab that pulls up the pop up. Most likely they did something to the add to watchlist option to not recognize items already in the list. At least clicking this option multiple times does not create duplicates in the watchlist.
