In NXT, the lifetime gift summary double counts soft credit gifts. The best part of NXT is not having to go into the database and to get a gift summary. If the giving total in NXT is displaying incorrectly, you then have to confirm the record's true gift total by going back into RE database.
For example, I have a record who only has soft credits to her account worth $17k but in NXT it gives her credit for the $17k and because she is also the soft credit recipient she is credited again, which creates $29k displayed. The two spouse records show different totals.