Are you clearing your app cache regularly? Instagram's algorithm should theoretically filter out seen content, but it definitely glitches sometimes - the app doesn't always register that you scrolled past something, especially if you're jumping between tabs or the connection stutters. Try clearing the app cache (Settings > Apps > Instagram > Storage > Clear Cache on Android, or offload the app on iOS), and if that doesn't help, try unfollowing some accounts temporarily and re-following them, which can reset what the algorithm thinks you've engaged with. If it keeps happening after that, it's likely just Instagram being Instagram - their recommendation system isn't perfect, and sometimes you just gotta accept that you'll see the same reel twice.