Yes they'll shoal together ... they're so close in appearance that it doesn't make a difference to them they are not the same species. I actually like the look of neons and cardinals mixed. I think it looks nicer than a school of either or.
75g Planted Barbs Denison, BlackRuby, Tiger, Albino Tiger, Green Tiger, Cherry, Gold, Checkered, Odessa.
NonBarbs Cardinal, Neon, RummyNose, Bloodfin Tetras, Z. Danios. 1RTS. Amano, Bamboo, Ghost & RCS. 20g Long Shrimp Tank RCS, Tiger, Amano.