What's the right way to use hyperUnique type field on metabase?

I test on the example database Wikiticker, there are two fileds ‘User’ and ‘User Unique’
‘User Unique’ is the hyperUnique type field of ‘User’, here is the config .

when i query ‘Number of distinct values of User Unique by Channel’ , the result is
ar.wikipedia 1
bg.wikipedia 1
be.wikipedia 1

when i query ‘Number of distinct values of User by Channel’, the result is
ar.wikipedia 118.35
bg.wikipedia 33.27
be.wikipedia 15.06

so , is the query ‘Number of distinct values of User by Channel’ the correct way ?
which means when i query on metabase, i should just query on the raw field ‘User’ rather then the hyperUnique type field ‘User Unique’.