I just was importing ~480 photos and I noticed that 6 or so of these photos were grayed out because they were "suspected duplicates".
They are definitely not duplicates. I made these photos today. I checked that the catalogue does not have any old photos incorrectly stamped with today's date.
I would assume that suspected duplicates at least involve comparing hashes of photos. For 6 out of 480 false poistives it should be a very weak hash even taking in account that I have ~300K photos in my catalog. So really sounds like a bug for me. Also I don't remember seeing anything like this in ~10 years that I use Lightroom.
The SDK will be updated later this week (June 13). The update contains a fix for this issue. Please download and the latest version of your application via the Adobe Creative Cloud Application or your respective device app store. If you do not see the update (Mac and Win) you can refresh your Creative Cloud App with the keyboard shortcut [Ctrl/Cmd]+[Alt/Opt]+[ R ]. Note: App store availability can take several days for the update to appear and be available. Thank you for your patience.