Some sets of twins resemble each other (7,5)

I believe the answer is:

several times

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'twins resemble each other' is the definition.
I can't tell whether this definition defines the answer.

'some sets' is the wordplay.
'some' becomes 'several' (similar in meaning).
'sets' becomes 'times' (timing is a kind of setting).
'several'+'times'='SEVERAL TIMES'

'of' acts as a link.

Can you help me to learn more?

I've seen this clue in The Everyman puzzle in The Observer.

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