For those searching for a solution via internet search: It's now possible within Overpass: http://overpass-turbo.eu/s/EYC // return keys that don't have same values [bbox:{{bbox}}]; nwr[highway=footway][name]["name:en"]["name:ga"] (if: t["name"] != t["name:en"] && t["name"] != t["name:ga"]); out geom; I'm sure it can be developed further.

For those searching for a solution via internet search: It's now possible within Overpass: // return keys that don't have same values [bbox:{{bbox}}]; nwr[highway=footway][name]["name:en"]["name:ga"] (if: t["name"] != t["name:en"] && t["name"] != t["name:ga"]); out geom; I'm sure it can be developed further.