If you have
Forgotten Realms Unlimited Adventures set up to play hacked modules, there's
The Topaz Championship (topaz.zip on the
UA FIle Archive), a short adventure in Rokugan (
Legend of the Five Reams), from three different perspectives, IIRC.
Not necessarily opposing, but:
Life Is Strange: Before The Storm shows how life was from Chloe's perspective after LiS's protagonist Max bailed on her in the past.
In
BioShock 2 you play from the perspective of one of the Big Daddys that you were fighting in BioShock.
*SLIGHT SPOILER* In
Hotline Miami you also play as Biker or Motorcycle Helmet Guy, who appears as an opponent of the main protagonist.
In
Batman: Arkham City you play as Batman as well as Catwoman, who are just as much allies as opponents, but have their own views, also putting each other into different perspectives. Not sure how relevant that is in the game though, as I've only played a little so far.
Max Payne 2 has a level in which you play as "femme fatale" Mona Sax, although I don't remember if that adds much in terms of opposing POVs.
The same goes for
The Last of Us where you also switch protagonists halfway through, though they're not opponents either, just gives you a bit more distance from each of their POV, if you've put yourself in the shoes of both of them, knowing things that the other one doesn't. But all that's probably stretching the definition of what you're looking for?
Also,
Spec Ops: The Line,
Far Cry 3 and
Far Cry 4 are undermining the heroic soldier trope by occasionally confronting the player with different viewpoints or realities that don't quite fit this narrative.