Kenny Chesney and Tim McGraw have added a second date at Gillette Stadium in Foxboro, Mass., to meet demand for their Brothers of the Sun tour. The performers were already booked at the football stadium for Aug. 25 but have announced another concert there on Aug. 24. Tickets for both shows go on sale Saturday (Dec. 3). That on-sale date also applies to the stadium shows in Dallas, Philadelphia, Pittsburgh, Chicago, East Rutherford, N.J., and Detroit. On-sale information for the remaining dates will be announced in the coming weeks.