Appear with the greatest film doubles (10)

I believe the answer is:

lookalikes

'doubles' is the definition.

'appear with the greatest film' is the wordplay.
'appear' becomes 'look' ('look' can be a synonym of 'appear'**).
'with' means one lot of letters go next to another.
'the greatest' becomes 'ali' (film about Muhammad Ali).
'film' becomes 'kes' (I've seen this before).
'look'+'ali'+'kes'='LOOKALIKES'

(Another definition for lookalikes that I've seen is " doubles?".)

I've seen this clue in The Guardian.

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