separate user tables is always a bad idea.
one of the basic concepts in database design is to avoid duplications.
any time you find your self creating a duplicate (table , column...) in your database, stop!! there is a better way.
in the case of a duplicate table, the better way is using a column to define a unique attribute. in this case a user level.
in the case of a duplicate column, the better way is to use a linking table instead.
Data Normalization is the main goal of a well designed database.
Duplicates are messy, and prone to causing issues.