Searching for say KAtomic it has two entries in Discover. One has the Apt/Snap/Flatpak and the other the AppImageHub package. They are not together because KNS does not get the appstreamid from appimagehub. Somewhere along the twisty maze of abstractions all alike this should be resolved.
It's not that twisty, OCS never provides the appstream id and as far as I know it's not even being extracted from appimages.
I guess it's in kns that the bug should be, I'll be happy to include it in Discover as soon as it's available. Dan, will you take a look into it?