It strikes me as odd that, where any playwright worth their salt wouldn't think of trying to publish a play without first having actors read it and mounting a production of it, most editors don't think twice about doing exactly that. Having finished a collation of three quartos, I'm fairly confident in my familiarity with the text (here I mean textual object), but the process of collation is no necessarily the most conducive to producing a functioning edition of the text.
I have previously commented on the relatively clear evidence for multiple authors in Merry Devil. The names are often times just plane wrong: surnames are inconsistent, or in the case of this afternoon's discovery, a character refers to another who simply isn't in the scene. If it was a clown, you might be tempted to brush this off as a malapropism of names, but in what I have dubbed scene 9, Peter Fabell calls Harry Clare "Ralph." There are already two Ralphs in the play, of course: Sir Ralph Jerningham, Frank's father, and Brian's man, Ralph. This isn't the sort of thing one would expect someone of Fabell's status ad knowledge, which is the foundation of his status, to get wrong.
So we paused for a moment to make sure that I hadn't simply let this typo slip through, and sure enough, there was the reference to "Raph" right there in Q1. Obviously this needs to be amended to "Harry," with the appropriate footnote that Q1 has Raph here, and that it is probably an error in the script or a compositor error.
Again, remember what Stern was saying about plays being cut for touring and some characters being cut or combined. It is completely plausible that this "typo" is the result of the King's Men editing the script for touring and creating a mashup character out of several others. It is also possible that it is the result of the scrivener of the fair copy missing the in-text reference to a character not present in the scene. One can't rule out simple compositor error either. I don't know how the mistake got in Q1, but it took my cast members trying to make sense of something they saw as inherently senseless to figure it out.