Well, I can't say that I have ever seen latezonatus that small before, but here is what I see.
That orange spot on the tail surrounded by black then white, is a definite juvi latz thing. The fact that the orange is different than the yellow on the nose and pecs is more convincing.
Although they are young, the body shape is more polymnus complex shape than clarki complex shape.
If it were a polymnus or sebae the middle stripe would be slanted instead of straight up. Juvi latz don't develop their "wide band" until later.
I am guessing that the dealer is telling you they are latz. I don't see any reason not to believe him.