Note their confusion, both one and the other (6)

I believe the answer is:

either

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'both one and the other' is the definition.
I can't tell whether this defines the answer.

'note their confusion' is the wordplay.
'note' becomes 'e' (musical note).
'confusion' is an anagram indicator.
'their' with letters rearranged gives 'ither'.
'e'+'ither'='EITHER'

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(Other definitions for either that I've seen before include "could be one of two" , "Each of two; moreover" , "No matter which (of two)" , "One of two alternatives" , "Choice of two" .)

I've seen this clue in the Evening Standard.

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