There are already chosen tags in autocomplete list

If user selects the tag and enters it again, it does not disappear from autocomplete list.

Steps to reproduce:
1. Enter some existing tag in tag field, for example 123
2. Click on this tag in autocomplete list
3. Enter this tag again in tag field

Actual result: This tag is shown again in autocomplete list, though it was chosen already.
Expected result: If tag was chosen already, it shouln't appear in autocomplete list until user deletes it from chosen tags.