Good point. Googling "Dost thou havest a " turns up two results, one of which is Eliezer's comment.
On the other hand, my instincts aren't perfect. I'd have bet that "havest" wasn't a word, but it is. "Hast" is a contraction of "havest".
I was wondering whether the problem was that "dost havest" is redundant, but "havest thou a" doesn't turn up anything period.
Yeah, “dost thou havest” would be much like “does he has”...
Here's the new thread for posting quotes, with the usual rules: