Here is a look back at a selection of players who have turned out for both sides down the years. How many of them do you remember?
5. GREG FEE
Greg Fee was a solid centre half. He had a spell on loan at Orient while at Sheffield Wednesday but signed for Mansfield in 1990 and over four rollercoaster years experienced a promotion sandwiched by two relegations. Photo: JPI
6. STUART HICKS
Centre half Stuart Hicks played 78 tims for Leyton Orient. But his time at Mansfield between 2000 and 2002 was hit by injuries, playing 25 times, and he ended up retiring from the professional game and seeing out his career at Hucknall Town. Photo: JPI
7. LUKE O'NEILL
A hugely popular full back at Mansfield and winner of a Chad Readers' Player of the Year award, he helped Stags into the play-offs in 2011/12 but his sparkling displays earned him a move to Championship Burnley for an undisclosed fee. He is now on the books of Stevenage. Photo: Justin Setterfield
8. LEE ANGOL
Despite so much promise, Lee Angol's career never caught alight at Mansfield, where injuries held him back. Yet he did score nine goals in 29 league appearances. He had two seasons at Orient from 2019 to 2021 and is now with Bradford City. Photo: Naomi Baker