Hi Nima,
I think screen name should really be unique.
You see there can be people with the same first and last name.
If you allow the users to have a same screen name. This can happen.
Example:
There are 3 users signing up in forums.
- User #1: John Smith, with screen name john
- User #2: Joe bloggs, with screen name Joe
- User #3: John Smith, with screen name john
Situation:
User 1 posts in a forum, User 2 replies, User 3, having the same name as User 1 posts and flames user 2. User 2 gets angry at User 1. He doesn't know that User 1 and User 3 have same names.
In this situation it is wise to have a unique screen name.
I hope this helps.
