Actually, Borda calculates a vote count for each candidate which seems not to rely on the seat count (the value of the "-s" option). I tested this for all votings with seat numbers from 1 to 4. In all cases the calculated vote count did not change depending on the number of seats. This is also expected behavior if you look at the definition of how Borda works: http://www.openstv.org/borda-count