No, that's not a mis-spelling. This post is going to be talking about what is often called "troupe-style" roleplaying.
The most common style of play in RPGs involves a player playing a single character until that character dies or retires. Then they create another character and plays through their adventuring life and so on.
Troupe-style play gives each player multiple characters to choose from for any given adventure. So if you were playing a Star Trek RPG, you would play your Starfleet Marine for a combat mission, but bring your Diplomacy Corps officer for a diplomatic mission. Or maybe your pilot who just happens to speak Romulan, since the diplomatic mission takes place near Romulan space.
For those following Barking Alien's Muppet RPG as he's posting it on his blog, you might notice that each player begins play with multiple characters. While each player participates in every scene/sketch, they do so as different characters.
Old School gamers already did something like this back in the day, pulling out one from a binder of character sheets depending on the difficulty level of the dungeon and the specific roles that need to be filled. MMO gamers do something similar with their "alts," bringing in their "tank", "DPS", or "healer" into play as needed.
It can also be used on a short term basis in a regular game to give all the players something to do. For example, in a recent D&D session (a friend of mine is running the game, not me) 3 of the 6 characters were called on to serve as the prosecution, defense, and judge in a trial. Which left 3 players (including me) with nothing to do as this trial scene played out. So my friend gave us witnesses to play so that we could be part of that dramatic scene, even if our regular characters weren't there.
Troupe-style play is also very Ozzy. While some series maintain a consistent core cast, there is very little consistency in the cast of an Oz story. While everyone remembers the classic adventuring party of Dorothy, The Scarecrow, The Tin Woodman, and the Cowardly Lion, that grouping has never occurred since. In fact, no more than 2 of these characters have ever adventured together again in the Baum canon (typically the Tin Woodman adventures with the Scarecrow, or Dorothy teams up with the Lion).
Baum would even change up the cast in mid-story. In The Patchwork Girl of Oz, he trades out the Woozy and the Glass Cat for Dorothy and the Scarecrow (an odd exception to the pattern noted above). So if you've got a player who is having a hard time settling on one character, you might want to let them create two and let them play in alternate adventures or find points in the story where they can switch off.
And one of the cool things about doing this in AiO is that even if a character isn't present, they can still have an influence if they are on another character's Friends List.