One of the great honors to bestow upon a player is to have his jersey retired. It is an assessment by a team that this player did so much for our team that no one should ever wear that number again.
Now there are some players such as Kobe Bryant or Tim Duncan whose entire careers are with one team, and it's not to take away anything from them. However there are some players who accomplish a legacy with more than one team, and their jerseys are retired by both.
There have been 10 such players in NBA history. The following slideshow details who those players are.
There are three jerseys not mentioned. I'll mention them here to avoid confusion.
Both the Orlando Magic and the Sacramento Kings have retired the No. 6, "The Fans." Since the "fans" are not technically a player, and even if you do want to argue they are, they are different "fans" so that one doesn't count.
Michael Jordan has had his jersey retired by Chicago and by the Miami Heat for "contributions to basketball." Since he never actually played for the Heat, I did not count him.
Pete Maravich has his number retired by both the New Orleans Hornets and the Utah Jazz. He actually played for the New Orleans Jazz, which is why his number ends up getting retired by the city's present franchise and its past franchise.
The other 10 players actually played games for both franchises. They are listed in alphabetical order to avoid any argument about who should be ranked where.