Nectarine Blueberry is a menu name rather than an established cultivar. There is no breeder release behind it, no seed catalog entry and no stable genetic record, which means a jar carrying this label tells you almost nothing about the plant inside. Treat the cultivator and the batch panel as the real information, and treat the name as packaging.
Where It Comes From
Names like this usually arrive one of two ways: a producer's unreleased in-house cross that never got documented, or a retail label applied to an unnamed phenotype because it needed something to sit under on a menu. Either way the record starts and ends at the shop.
Only the producer who put it on the shelf can say what it actually is, and that is worth asking before you pay for it.
The Cross
No breeder is credited and no lineage is published. The two halves of the name do point at real, documented things, though. Blueberry is a heavily documented indica-leaning hybrid from DJ Short and one of the genuinely foundational berry lines in the catalog. Nectarine Jelly is a separate, documented cultivar built from Peach Panther and Governmint Oasis.
Neither is the same plant as Nectarine Blueberry, and neither lineage should be assumed from the name alone.
The High Rise Take
Nectarine Blueberry is a name without a documented line behind it. If berry is what you are after, Blueberry is the place to start, and Nectarine Jelly is where to look for stone fruit. For anything sold under this label, the cultivator is the only thing on the package worth trusting.