Malt-o-meal makes excellent imitations of name-brand cereals. For example, Golden Puffs = Kellogg's Honey Smacks -- completely indistinguishable, but much cheaper. They make about 30 different kinds of cereal.
Anyone in my family can tell the difference between Kellogg's raisin bran and M-o-m, so I think it is safe say some people would notice a counterfeit cereal.
Now I'm hungry...