There's possible and there's likely to happen in nature. two opposing planets in symmetry you'd have to have symmetric mass all around to cancel the forces out.

There's possible and there's likely to happen in nature. two opposing planets in symmetry you'd have to have symmetric mass all around to cancel the forces out. One side will have the galactic centre on and the other won't might even be enough of a tiny imbalance to disrupt the orbits as you say.