You're describing a different in product at this point though (i.e. style of bread, etc) rather than a "brand". Again, products where generics are literally the same and simply have a brand (ibuprofen for example) are what you were talking about and unless you're entirely brain poisoned there's no difference between Advil (brand) and the generic chemical!

A lot of the different products in stores are really made by a small number of conglomerates. Those companies are making new products all the time through what are essentially little internal planned economies. They are doing it to stave off competition, but these aren't products being developed in "the marketplace". They are deliberate planned processes.

No reason to believe the couldn't happen under a state run planned economy.