I just went through the standard registration process on your site and I can see the issue. From this page:
/index.php?option=com_easysocial&view=registration&layout=steps&step=1&Itemid=780
The first field is "* Nome:". That seems to indicate you want the user's full name. However, the actual field HTML looks like:
<input type="text" size="30" class="form-control input-sm" id="first_name" name="first_name" value="" data-field-jname-name="" placeholder="Seu Nome">
EasySocial thinks the user is providing only their first name here, not their full name. To my knowledge, EasySocial doesn't have a generic "name" type of field, only a first, middle and last name field. I'm not sure how you've set that up so that the middle and last name are missing, but it's not standard.
JFBConnect will automatically set the users first, middle and last name. Depending on how you display the user's first name or first/last name combo, I can see how something may look to be duplicated.
In the admin area, if you go to Users, is the proper name shown for the user? If so, that would indicate we're doing things correctly, but the display on the front-end is just wrong.
Thanks,
Alex