Recently was performing a spell from Golden Secrets of Mystic Oils, which required for its production a "Seal of Mephistophilas" (sic.) That sounds awfully like Mephistopheles to me; and indeed my search immediately suggested I meant Mephistopheles. These same search results also turned up this page, which really sounded like the same thing was being talked about.
The seal of Mephistopheles above was published in a German grimoire, and reprinted by J. Scheible in his twelve volume anthology of occult works "Das Kloster" in 1846. It was reproduced by Butler in her book "Ritual Magic" (Plate VII). It is the same seal that appears in "The Sixth and Seventh Books of Moses", where it is shown greatly corrupted by the carelessness of copyists.This seems a good thing to note: in the days before photocopies or scans these seals all had to be drawn and redrawn, and even when produced by a careful copyist might bear little resemblance to their original design, like those portraits of Benjamin Franklin that the man himself remarked on.
As for a seal of Mephistophilas, it does appear indeed to be one and the same as the seal of Mephistopheles. (And is also found spelled Mephistophilis and Mephistophiles.)
As I recall, the Obeah Bible actually needed to have the pictures redrawn because they were printed in such poor condition -- and I think even then, because they were copies of bad copies, they found themselves with some, shall we say, differences between them and the original versions that predate De Laurence. Example below: left is from De Laurence's "Great Book of Magical Art (aka Obeah Bible)", the other from Agrippa:
Still, I think it's kind of like the matter with magical formulas where, even if you get them wrong, they can still work as well as if you'd been right.