Is "may or may not" redundant?

(Note: I'm not talking about the same kind of redundancy as in this question).

Is "may or may not" correct, or is it a redundant version of "may or not"? I've seen both, and I don't know which one(s) is (are?) correct:

• The position of lecturer is occasionally given to individuals [...] who may or not have a doctoral degree.
• The position of lecturer is occasionally given to individuals [...] who may or may not have a doctoral degree.

If you take the phrase as a whole idiom—rather that the sum of its parts—it is not redundant. The point of its use is to highlight a common assumption that does not apply. In your example, it could be assumed that a lecturer would need a doctoral degree, and the idiom dispels this notion.

If I read "may or not", I would suppose that it was an error. I am startled to find that other people find it acceptable. (UK English, in case that is relevant).

The "may or not" version generates problems like: "He must do what he may or not a thing will come of it" vs. "He says he will fish; he may or not like the experience." You have to read on too far into the sentence to resolve whether the "or not" goes with the "may" or the rest of the text.

Perhaps because of this, the form I've heard most often is "may or may not" (which requires more exotic conditions before it becomes difficult to parse).

If you make the verb explicit: "may fish or not", then the "or not" form is quite common also.