Well,
there is a 50% chance that it IS het pied, and there is a 50% chance that it IS NOT het pied (meaning, just a normal type)
IF it is in fact a het pied, then it would be like breeding Het Pied to Het Pied. You would have the probability of getting 25% pieds, and the rest would be possible hets.
If you hatch out what appear to be all normals, then you would have 50% possible hets and 50% possible normal type...because you can't tell which ones are het and which ones are normal.