REALLY LATE EDIT:

The ONLY possible ways to get what he got with that clutch are:

Platty is a Recessive and the Butter was het
or Platty is a different gene than the Lesser, meaning there would only be a 50% chance of any offspring having that Platty trait (including the normals)


On the second option, if that were the case then you could breed a platty to a normal and get a platty daddy.