Related Clues:

• Tweedledum, for one
• More than a look-alike
• Make a backup of
• Contract clone (whose abbreviation hints at this puzzle's theme)
• Bed in old sitcoms
• Mimeo
• One of the Gemini
• Copy, of a sort
• Dolly the ewe is one
• Biological duplicate
• Same-aged sibling
• Make a copy of
• Any 'Jurassic Park' dinosaur
• Doppelgänger
• It's all the same