Note duplicated carbon copy (5)
I believe the answer is:
mimic
'copy' is the definition.
(I know that mimic is a more specific form of the action copy)
'note duplicated carbon' is the wordplay.
'note' becomes 'mi' (as in 'do re mi').
'duplicated carbon' becomes 'mic' (I can't justify this - if you can you should believe this answer much more).
'mi'+'mic'='MIMIC'
Can you help me to learn more?
(Other definitions for mimic that I've seen before include "'Copy, imitate (5)'" , "Imitate, especially for satirical effect" , "Imitate for humorous reasons" , "Act like" , "Impressionist" .)