Since 2015, all homegrown players - those developed at an academy of a club in the English football pyramid for three years or more - are presented with an official Nike match ball to mark their first appearance in the Premier League, as well as recognising the development and support given by their clubs, academies, friends and family along the way.
Sean made his first Premier League appearance at Liverpool last Boxing Day and received his ball, complete with a personalised, engraved plaque, in September.
Matty's top flight bow came against Manchester United last month and he marked it with the only goal of the game in a man of the match display.
His ball arrived at the Magpies' Little Benton Academy soon afterwards, and has now been placed next to Sean's. "His is up at my mam's house, next to our man of the match trophies," Matty told nufc.co.uk. "We both have a man of the match trophy, and now, to have the Premier League balls next to each other, I guess will be great to have at home and probably a proud thing for my mam and dad when they walk in the house - to be able to see them and what we've achieved so far.
"I imagine I'll keep (memorabilia) over the years. I'm still young and new to everything so I'm not really thinking about keeping stuff or swapping shirts - I'm just trying to take everything as it comes. I've played three games in the Premier League now and I think the biggest thing for me is to try to keep playing and play as many games in the Premier League as possible over my career."
Reflecting on the debut, which came for his boyhood club at St. James' Park, alongside his brother in the heart of the Magpies' midfield, Longstaff smiled: "I think every kid's dream when they're growing up is to play in the Premier League and to score against the big clubs, and for it all to happen in one appearance is a bit surreal.
"I think it has (sunk in) a couple of weeks down the line; you go to Chelsea a week later and you have to get over it quickly because these are the best players in the world you're playing against, so if you're still thinking about the Man United game then you're probably going to struggle.
"To be honest, from hitting the ball I still can't remember much other than the celebrations, but it was more surreal than anything."
As well as the debut balls, the Premier League - in association with Cadburys - also present awards to players who reach 100 Premier League appearances, plus 200, 300 and every century mark thereafter.
Last week, Dwight Gayle received a special medallion and a plaque to commemorate his 100th appearance, and Longstaff would love to reach that milestone one day.
"You see Dwighty, the career that he's had has been unbelievable. He's got his 100 appearance award now and if I could get that, it would be pretty amazing," admitted the 19-year-old midfielder.
"But I'm a long way off and there's a lot of hard work still to do to get to that point."
