"Ghost Sequence" (Duplication) in Grid View

I had an issue just now when listing a grid view of items to see, where a sequence of items was then followed by an identical sequence of the same.
I thought the person had double-uploaded but when I added an ID to one in the second sequence (to clear its submission; I had ctrl-clicked a number of them open) I found just after it had also acted on the equivalent item in the first resulting in a withdrawal of the first id I had done for it and replacement by the same id (which I had submitted supposingly on the second copy).
I then hovered over items in the grid and the duplicated sequence in the grid view had the same URLs so the second set was a ghost sequence of the first.
When I did a refresh the duplication disappeared.
So clearly not reproducible at will, but you’ll want to think about the underlying code and how it occurred. Presumably could occur in List View too.

sounds like the same thing as what has been previously reported in https://forum.inaturalist.org/t/observations-displayed-multiple-times-when-scrolling-in-grid-view/504 (and many other threads).

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Well that does look old :)
Ghost records can be created when doing an SQL join against a table that’s meant to uniquely join but has some non-unique elements (here presumably of a transient nature). I’m not sure if that’s the situation here but it’s a suggestion to consider.

joins are unlikely the root cause. it’s more likely some sort of race or caching problem. i bet the reason that it hasn’t been addressed is because it’s not worth the effort. there were plans in the past to redo the Explore page anyway. so whenever that happens (i would assume after the v2 API is done), that’s probably when anyone will even attempt to address the issue.

If there’s a revamp envisaged that’s very likely the thinking! Cheers, David

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closing to focus at existing bug report