When searching for editors in the edit search, I managed to end up with duplicate recent items.

Steps to reproduce:

• Load https://musicbrainz.org/search/edits
• Select "Status" and set it to "Open" (this bit is probably irrelevant, I only included it to stop the edit search taking forever)
• Select "Editor" and click in the input field
• If there's already some recent editors listed, select "Clear recent items" first
• Enter "ModBot" and select the result from the list
• Submit the form and wait for the page to load
• Select "Editor" again and click in the input field again

Expected result: One entry is shown, "ModBot"
Actual result: Two entries are shown, both "ModBot"

Reproducible in both Opera and Chromium for me.