Albert Belle hit 50 doubles and 50 homeruns in the same season in 1995. What is the closest any other player has come to doing this?

Alphonso Soriano, in 2006, had 46 Home Runs and 41 Doubles.

http://www.baseball-almanac.com/hitting/hi4040c.shtml

Homer/Double stats aren't traditionally kept in baseball. 20-20, 30-30, 40-40, and 50-50 Clubs are Homer/SB stats.

Although no one except Belle has accomplished this, many players have come closer than Alphonso Soriano. Closest was Todd Helton, who missed by 1 HR in 2001, with 54 doubles and 49 HRs.
http://www.baseball-reference.com/players/h/heltoto01.shtml

In 1927, Lou Gehrig had 52 doubles and 47 HRs, and his miss by 3 HRs is the next closest.
http://www.baseball-reference.com/players/g/gehrilo01.shtml

Here's a list of all the 40-40 players:
Jose Canseco
Alex Rodriguez
Barry Bonds
Alfonso Soriano
https://www.baseball-almanac.com/hitting/hi4040c.shtml