Duplicating a pattern and changing to non-synced but images on copies of pattern are still synced

[pauldyke]

I have created a pattern in a block theme (create block theme plugin) and enabled overrides on an image. I later changed my mind about it being synced (because I cannot set lists to be overiden. I have clicked duplicate and unchecked synced. When I add a number of these patterns into my page and change one of the images, they change in all instances of the pattern on the page.