Naming Question

I have found a family record that I do not understand and hope someone can
help on this question.

In 1870 I have found a Christening record in Lengerich with the father last
name of PLEGGE and the mothers last name as PLEGGEN. I have never found the
mothers name in any other records. Could this be entered in error and the
mothers name is now unknown? If any body has a answer please share it.