Good eye there on spotting the mistake from the store.
The whole 'false julii' tracks out of a mistake made 70 years ago, when patterned Corys without masks were misidentified and sold as C. julii. When the mistake was discovered, julii had already become a common name in North America, at least. I bought 'julii' in the equivalent of walmarts when I was a kid.
Rather than start importing the fish as what they are, the 'false' thing was tacked on. There is a real Corydoras julii that is rarely imported.
The same name foolishness affect the famous Kribensis Cichlid. The one you buy as a Krib was a botched identification around the same time. Their species name in Pelvicachromis pulcher. The fish the hobby thought they were is P. kribensis, and it gets no respect. I think it's a much nicer fish, bit no one buys it because they think it's common.
Both julii and kribensis were victims of identity theft, and the mistakes of importers long gone turned their scientific names into common names.
The real Corydoras jullii is happily swimming in a region rarely visited by fish collectors because it's off the beaten track. When I see a tank labelled as containing trilineatus, I figure the store owner knows something about Corys.
When I see "false julii" or even julii on a tank, I figure they don't.