The Monkees) adopted sensational spelling in an effort (by either themselves or their record labels) to capitalize on a fad. The Turtles successfully resisted an effort by their label, White Whale Records, to name them "The Tyrtles."
The Monkees adopted an unconventional spelling as a marketing tactic, mirroring a popular trend.  Similarly, The Turtles resisted a change in their name, demonstrating a proactive approach to maintaining their identity.