The manual for Spore says exactly: "You may have multiple Spore accounts for each installation of the game."

Users, however, have been complaining that doesn't seem possible, and while it took a while, an EA rep finally admitted "our bad": "That section in the manual was a misprint and will be corrected in future printings of the manual. There is one Spore registration/account per game/serial code so you are correct in that you cannot make multiple accounts at this time."

Pft. A misprint??? You gotta be kidding me. Full text on:

http://www.techdirt.com/articles/20080912/0031172248.shtml
http://www.techdirt.com/articles/20080912/0031172248.shtml
http://www.techdirt.com/articles/20080912/0031172248.shtml