I've been researching the german civil and church records from Satzvey, Rheinland, Prussia and have found my ancestor's birth and marriage records as both "Sieben" and "Siepen." I am not sure if there was a change in the spelling of their name or if this is a common thing. I do know that the soundex codes for b and p are the same. I also have a mini German-English dictionary that says that these letters were frequently interchanged.
Has anyone else experienced this? Are there any German speakers who can comment on this observation?