Hi Ed,
From family conversations, the name originally was spelled "Ptak" and upon emigrating from Poland to the U.S. some members of the family added the "e" although it remains "silent". Another theory is that the "e" was actually a spelling error made at Ellis Island and family members decided to leave it that way.

Research I've done show Ellis Island records of my great grandparent's arrival and the name is spelled "Ptak", however, some years later, on my grandfather's draft registration its Petak!