When email already exist the system allow you to define a new user with different email address or link to existing user with a simple login (username and password).

Still, you can also create a button to link account when user is already logged in, see docs at http://docs.easy-profile.com/index.php/article/social-connect-intro

Can you please help me on it further, i m still unable to fix it.

This is a normal workflow, you don't need any fix.

if email already exist you see a form with 2 options (see screenshot)
1) registerer new user with another email address
2) link a existing user by filling username and password

Is possible to add buttons to link account when user is already logged in by adding in any article or module the code described in "Link Existing Profile" section at http://docs.easy-profile.com/index.php/article/social-connect-intro

Hi,
username and password are generated by the system, you can change it from edit profile page.