C. Dale Young writes, in his post "Lies and Garbage" (and in his role as poetry editor of New England Review):
"Why do writers lie in their cover letters? I mean, they not only lie but they lie like dogs. Not all of them. Not even the majority of them. But the ones that do just about kill me. It is never a good idea to lie about something like having work in The New Yorker and POETRY. These can be checked in less than a minute. And even if your lie gets your work past the screeners and into the hands of the poetry editor, s/he will know almost immediately that you are lying. So weird."
My comment to him:
1) I, too, am astonished that somebody would lie about the really biggest names, where it is, in the age of the web, astonishingly easy to be caught in one's lie.
In composition classes and academic work, it is easy these days for students to steal essays from the web (or essay-like texts from blogs), but it is also incredibly easy for their teachers to find them, too (and the stolen material sticks out like a sore thumb, because of the change in style—and, with my students, the sudden absence of the common mistakes made by German speakers). In fact, the English Seminar in Basel subscribes to a service that can identify plagiarized texts—the flip side of students' buying essays from web services.
2) Why do editors need bios at all? I just read the guidelines page at NER. It does not ask writers to submit a bio in their cover letters. Have you thought about asking people to NOT send bios?
What is the purpose of a bio with a submission to a literary magazine, anyway? If the editors are really serious about the idea that they look only at the poems themselves and not at the names of the poets who wrote them, then a bio should be superfluous. If a good bio increases the poet's chances of being published, then the editors are looking at more than just the poems themselves, aren't they?
Of course, even without bios in cover letters, editors will still recognize the names of many of the poets who submit to them. But short of blind submissions (as in prizes), there's nothing to be done about that.