Each consignor normally gets one settlement per sale, which is run 1. If a settlement has to be redone — for example a sale correction came in after the first check was cut — a new run is created with the next number (run 2, run 3, and so on). The combination of sale, consignor, and run number is unique, so you'll never see two run 1s for the same consignor on the same sale.
A re-run does not erase the original. The earlier run stays in the record (typically marked VOIDED or RE_RUN) so the paper trail stays intact.