Adding roles on existing user, not over-ride the current role

Replies: 0

Hello Please kindly help me again.
Now I need to add role for existing users, without touching existing roles.
I thought it could work if I selected,
[Yes, add new roles and not override existing one]

http://prntscr.com/oewtqr

But, it did not work for me..
CSV file : I added only a [new role] to be added
the result after importing: Current role is remian, no new role is added

can you please help me how I can make it happen?
I am sorry if I over looked instruction in documents..

Best regards