I've got a theory! Mixed berry products (like this

)

are actually whatever flavor the label machine failed on. As in, the flavor manufacturers make some flavor like strawberry, then the machine smudges all the labels saying "STRAWBERRY" into "BtDhtjTFD" before storing them in the warehouse. Then some guy comes in and has no clue as to what the flavor actually is, so just calls it "MIXED BERRY".