Dave Watson's Magpies had beaten Fleetwood 5-1 in the opening game of the summer, but this was a closer affair at Little Benton.
Indeed, United couldn't find an opening goal in the first half - although Thomas Cole came close.
However, three minutes into the second period, Sorensen broke the deadlock with a simple finish.
Then two minutes later the Danish striker doubled his and Newcastle's tally - although there was nothing routine about this one as he jinked into the box before scoring in style.
Watson named two completely different outfield XIs as United continue to prepare for the SuperCupNI, which starts later this month.