Fixes duplicate users in search suggestions

What does this MR do and why?

Fixes duplicate users in search suggestions

In some cases, the filtered search may display duplicated users as the list of suggestions is not correctly deduplicated.

This fix passes a "value identifier" to use when comparing users to eliminate possible duplicates.

Changelog: fixed

This fixes an issue discovered at !136330 (comment 1787527987), and I tested the integratation of the fix at !145822 (closed).

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Screenshots or screen recordings

See !145822 (closed)

Related to #378633 (closed)