A. As of later September 2017, three batters have hit two home runs in an inning more than once.
They are …
Willie McCovey, who connected twice in the fourth inning for the San Francisco Giants against the Houston Astros on April 12, 1973, and repeated the feat in the sixth inning against the Cincinnati Reds on June 27, 1977.
Just a year and a month (ish) later, Andre Dawson hit two homers for the Montreal Expos in the third inning against the Atlanta Braves on July 30, 1978. The Hawk smacked two homers again in the fifth inning on September 24, 1985, when the Expos played the Chicago Cubs.
And finally, Jeff King turned the trick for the Pittsburgh Pirates, with his games coming less than a year apart. King’s first two-bomb inning came in the second frame of the Bucs’ contest against the Giants on August 8, 1995. Then, on April 30, 1996, King went deep twice in the fifth inning against the Reds.