Often times authors and lyricists will use homophones—words that sound the same as other words that mean something completely different—to give additional meanings to phrases. An excellent example is the line "The shops in mourning" from Dylan Thomas's Under Milk Wood. "Mourning" could either be heard as "mourning" as in grieving, or as "morning" as in the time of day.
When David Bowie sings "Now the workers have struck for fame / 'Cause Lennon's on sale again" he employs a homophone in his use of "Lennon." It can either refer to John Lennon, who released "Working Class Hero" in 1970, or to Vladimir Ilyich Lenin, the leader of the October Revolution way back in 1917. Interestingly, while the two men occupy vastly different roles in history, in this case they both reinforce a single meaning in the song rather than give two completely different interpretations.
Both names evoke socialist revolution in some way. In "Working Class Hero," John Lennon casts himself as the leader of a proletarian revolution:
And you think you're so clever and classless and free, But you're still f---ing peasants as far as I can see [...] A working class hero is something to be. If you want to be a hero well just follow me.
And a proletarian revolution was, of course, exactly what Vladimir Ilyich Lenin led in Russia in 1917. The international communist movement that Lenin inspired eventually reached all the way into Walt Disney's studios—the 1941 animators' strike was led by communist agitators.
While their names are (slightly) different, Lennon and Lenin both evoke the same sense of socialist revolution in "Life On Mars?" This makes the lines from the second verse highly focused on a single theme while still allowing for multiple interpretations. The literary theorist Umberto Eco has said that the best texts allow for multiple interpretations and act as "fields of meaning." Interestingly, Bowie's second verse acts as a "field of meaning" while remaining focused under the umbrella idea of the commoditization of socialism.