Sentry saves user name associated with a privilege in lower case. And when getting privileges of a given user, the query returns the privileges associated with a user in case-insensitive way.
Therefore, if there are two users, only differ in case, will have same privileges.
1) User user_1 is granted privilege "ALL" on a database DB_1
2) then User USER_1 has full access on that database,
The desired behavior is to keep user name case sensitive.