same surname marriage

marriage is a personal law issue and personal laws have custom playing an important role.

If society and custom permits, i think there is no hindrance.

ONce custom in your community/caste permits there is no bar for sagothra Marriage  and legally it is valid.Such a marriage  is not void. It should be proved to the satisfaction of the court that  custom  in your community doesn 't prohibit sagothra Marriage in the same caste/community you can  go ahead with the marriage. with the girl you love albeit  she belongs to same  gothra.

Court declares a marriage void as per law only.. it is neither void as per Personal law..Hindu/Muslim law and for that matter as per Special Marraige Act(which defines Prohibited degree and this one not falling in that category).. thus court would not declare such a marriage void..provided it's amongst consenting adults, sound mind, without fraud.... these being essentials of valid marriage

Surname need not necessarily same as gotra.

Gotras and surnames may be one and the same though marriages within Sagotriks are not permitted in Hindus

But we have to consider the lineage of Rishis in the gotras.  

If there is no link in Rishis, you can go for marriages.

But for a civil marriage unless and until they are closely related, marriage is permitted legally.

Dear suman,

  in our hindu law not given marriage prohibited grounds regarding same sur names and gothra's.is your friend can go for marriage with accaeptance of both familes with legally