I put a paper up for discussion on academia.edu.
A connection between Hittite ḫumant- “all, each, entire” and Vedic ubhau “both” was proposed by Puhvel in his Hittite Etymological Dictionary. He analyses ḫumant- as ḫu- + suffix -want- (PIE -went-). For the first element, he assumes an original meaning “both” and for the lexeme a development “both-having” > “all-having” > “all”.
This paper argues that there is indeed a common element *h2u- in both words, but that it's original meaning was "all".
Readers are cordially invited to join over there or to comment here.