I have a plugin which makes "undroppable" items, by cancelling the PlayerDropItemEvent.

It seems like now in 1.11 when I do this, the item will duplicate- though only up to a count of two. So a single item will turn into a 2-count item, but after that it remains at 2.

I don't think this is being caused by anything else my plugin is doing, but if there is any doubt I would be happy to make a simple isolated plugin for testing this issue.