Do we have this one already?

Authors recycle characters, plots, and motifs all the time. We know this. Sometimes the recycling job is extremely obvious, though, especially to those familiar with the author's earlier work. The character or plot is really familiar. An older work, or something filed under Canon Discontinuity or Old Shame has been strip-mined to create a younger, prettier work. It's a case of the author filing off serial numbers and hoping his readers don't notice the resemblance.

Literature

• Zilpha Keatley Snyder's Land of Green Sky was actually introduced in The Changeling, and the two female leads of that book were given a gender change to become Raamo and Neric.
  • Actually you're right, but with the wrong characters. Ivy is Raamo's sister Pomma; Martha is the Erdling Teera.

Live Action TV

• Taelons Da'an and Zo'or of Earth Final Conflict look and act suspiciously like the Telosians from the first Star Trek pilot.