Add config option to allow unique by language

Problem/Motivation

I would be helpful to have the unique comparison have the option of adding language to part of the query for unique.

Use case:
On a multilingual site, I should be able to have a page with the same fields set, but for different languages

Example :
Ford->Bronco in English
Ford->Bronco in Spanish

Proposed resolution

Add a language option that lets the user check off whether to include language in the query criteria.