2013 – For only the second time in major league history, brothers hit back-to-back homers in a game. In the second game of a doubleheader played in frigid conditions at Coors Field, the Braves’ B.J. Upton leads off the 5th inning with a homer off Jon Garland, and his brother Justin immediately follows suit, driving Garland’s next pitch over the center field fence for his major league-leading 11th homer of the year. Atlanta sweeps the twinbill over Colorado, 4 -3 and 10 – 2. The only previous instance of brothers going deep consecutively was Hall of Famers Lloyd and Paul Waner doing so for the Pirates on September 15, 1938.

This Day In Baseball

On April 23, 2013 — 2013 – For only the second time in major league history, brothers hit back-to-back homers in a game. In the second game of a doubleheader played in frigid conditions at Coors Field, the Braves’ B.J. Upton leads off the 5th inning with a homer off Jon Garland, and his brother Justin immediately follows suit, driving Garland’s next pitch over the center field fence for his major league-leading 11th homer of the year. Atlanta sweeps the twinbill over Colorado, 4 -3 and 10 – 2. The only previous instance of brothers going deep consecutively was Hall of Famers Lloyd and Paul Waner doing so for the Pirates on September 15, 1938.

Source
Baseball Reference April 23