Having multiple competing projects is not unheard of in the business world in general, and in high-achieving technology businesses in particular. Often, those outside the organization are only aware of the winning project, and the others are quietly discontinued, with many / most / all members moving to the winning team.

I know of several other prominent examples, but can't mention by name because I'd be breaking an NDA.

Also, Fuchsia is a successor, not a competing project, strictly speaking. It would be the "gauntlet" scenario if Google was running multiple ongoing projects all competing to "inherit" Android (which quite possible it does...)