For the Oracles and Frenzyheart, you can get to be exalted with both, but not in the way you'd expect. You probably know you can switch between the two. When you switch, the reputation you had with the old faction is preseved. SO, what that means is that if you get to Exalted with Frenyheart, then switched to Oracles, you'd still be able to switch back to your Exalted status with the Frenzyhearts. So, this is kindof a yes and no.
CANNOT get to be exalted with both Scryers and Aldor. You lose rep with one faster than you gain with the other.
You can get them both to Exalted if you wanted to be crazy. Just kill Booty Bay Bruisers till you get to the rep you want with the Bloodsail Bucaneers, then go kill non-Bloodsail monsters that give rep with Booty-Bay. (Venture Co. mobs should work, but you're in for a hell of a grind.)