Poll = head. "Poll vote" = vote by headcount, 1 man 1 vote. "Poll tax", originally, a fixed amount per head. In England, John of Gaunt tried that in 1377, with a few exclusions. Later attempts were graduated for the well-off, but with a general flat rate per head for the plebs. Most plebs had never paid any taxes before, so not surprisingly there were riots.
So presumably in Rehoboth some people had to pay for more than one person.