"Fluorescent Leach" and "Eddie" were the actual names Frank Zappa named his road managers. So, Mark Volman and Howard Kaylan used those names instead of "The Turtles." Eventually, after two albums on Warner Brothers and two albums on Columbia, they finally purchased the name. I think for like $35,000 or something. Since about 1983 they've been touring, under the name "The Turtles" featuring Flo & Eddie.
After a string of hits and international success, The Turtles folded in 1970. Mark, Howard and Jim Pons joined Frank Zappa's Mothers of Invention, for one of the most entertaining incarnations of that ensemble. Due to contractual restrictions made early in their career, Mark and Howard were prevented from using the name "The Turtles", as well as their own names, in a musical context. In order to circumvent this, they became "The Phlorescent Leech and Eddie" (later shortened to "Flo and Eddie").
theturtles.com/floeddie.html [no longer exists]
The Phlorescent Leech and Eddie is the first album from Flo & Eddie, released in 1972.