This is a new one. According to reports from ESPN's Ramona Shelburne and TMZ, the Lakers will hold a ceremony during their December 18 game against the Golden State Warriors to honor Kobe Bryant. As part of the celebration, the Lakers will retire both numbers worn by the future Hall-of-Famer—8 in the first half of his career, and 24 for the latter half. There is a short list of (non-Yankees) athletes to get their numbers retired, and an even shorter one for multiple numbers; not even Michael Jordan had the No. 45 he wore after his comeback was retired.
Bryant switched from his original No. 8 before the 2006-2007 season, and wore No. 24 (an early high school number) until he retired following the 2016 season. Bryant chose his original number for the Lakers because the No. 33 he wore his senior year of high school as a shout out to his father was already retired to honor Kareem Abdul-Jabbar.
While wearing No.8, Kobe won three NBA titles, and averaged nearly 24 points per game. While wearing 24, Kobe won two more titles, and added nearly three points per game to his average. That is to say, Kobe was pretty much dead on last summer when he told Shelburne which number he'd retire if had to pick:
It's pretty weird but the Lakers basically had to do this. There's no way anyone would have been allowed to wear whichever one went un-retired so you might as well hang 'em both up there.