Jon: Does this band know that its name is misspelled?
Rory: It's a stylistic choice?
Jon: To look like idiots? For Google to show results for "The Millennium" instead?
Rory: Maybe The Millennium with two Ns was taken.
Jon: According to Wikipedia, The Millennium with two Ns was a band, that released only one album, in 1968. I'm pretty sure The Millenium with one N could've been The Millennium with two Ns without any confusion.
Rory: Maybe they liked the name "The Millennium," but couldn't trademark it, like why Sci Fi became Syfy.