purim - Where did the "different bracha for mishloach manos" idea come from?

Rambam and Shulchan Aruch say you can send two types of meat as mishloach manos on Purim.

Yet somehow I (and many other people, apparently) were taught that the two different items have to be in two different bracha categories.

If this is a halachic folktale, does anyone know where it came from?