Find out who is having two ID in the list

Hi all

I want to find out who is having two ID under the same name.
I tried to search some post but couldn't get the same result as I need.

The requirements:

Any of the rows can't be removed and I want to add a check column to find out who is having two or more ID.
Prefer to only have one check column, if it's not possible, one helping column is okay. Thanks
It may has more people are having two ID.
One name may have two or more ID, we just need to find out who is not One name to One ID.

Could you please help me to have a look, thanks
Please see the attached sample list

bb1228