Most Celeste in my collection don't do two crops, first. Second, never seen a blackish purple Celeste. Fruit looks a bit large for Celeste. Shape not quite right for ones local to me (neck not long enough). Interior color not quite right. Celeste also isn't ripening this time of year for us, still got another 6 weeks to go.
My best guess is it's a relative in the ballpark of Black Mission, Black Jack or other genetically similar. Curious to see main crop. May be able to supply more specifics when it arrives in fall. Good news: these pics pretty much rule out about 80% of the possibilities, which is a very good thing