I'm all for changing the values of the duplicates and then alerting those users that the value was changed. Or, at least if I can find out if I have any dupes. I just don't want to lose anything without knowing about it :)
The query returned
usr_token = empty
dupes = 1701
I believe the dupes here would be all of the rows that have empty usr_token fields.
I ran the same query with the usr_key field and had the same results.