Hi, i have a question: it's possible to prevent registration from same ip?  

I wouldn't recommend it these days with users from mobile networks sharing dynamic IP addresses so often. You'd be preventing memberships from people who are totally unrelated.

Having said that, if you have a single IP address in mind (as opposite to something that always prevents the same IP addresses), you can put that IP address as a ban filter.

Go to the ACP, then MEMBERS > BAN SETTINGS > ADD BAN FILTER selecting IP Addresses

Ok, bad idea

Thank you very much  

... or use this to get aware of duplicates:

 

1 minute ago, Adriano Faria said:

... or use this to get aware of duplicates:

 

Wonderful!! *_*