This VR-3 Zone shall specifically permit single-family dwellings with a minimum lot size of 7,500 square feet per unit, if all lots are served by both community water and sewer systems. In addition to the single-family dwellings, the permitted uses shall be the same as the VR-1 Zone, except that duplexes may be allowed on corner lots where the lot area is in excess of 10,000 square feet.