Second selfs unfortunately stole gear (5,4)

I believe the answer is:

alter egos

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'second selfs' is the definition.
The definition and answer can be both people as well as being plural nouns.
Maybe they are linked in a way I don't understand?

'unfortunately stole gear' is the wordplay.
'unfortunately' is an anagram indicator (a bad or unfortunate spelling).
'stole'+'gear'='stolegear'
'stolegear' with letters rearranged gives 'ALTER EGOS'.

Can you help me to learn more?

(Other definitions for alter egos that I've seen before include "confidants" , "Soul mates" .)

I've seen this clue in the Sydney Morning Herald.

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