@DryFly1995 — good, that gives you real flexibility. For what you're planning, a single .375 H&H will genuinely do the whole list. It's the legal minimum for buffalo, hits plenty hard for sable and kudu, and in that thicker Save Valley / Coutada country your shots sit mostly close to moderate — so you give up almost nothing by leaving a flat-shooter at home. Load a good bonded or premium soft, a 300gr, for plains game and your first shot on buffalo, and carry solids for the follow-up. That's a complete kit.
The case for two rifles is comfort and insurance rather than necessity. A lighter plains rifle — a .300, .30-06 or 7mm — means less recoil over the many sable, kudu and plains-game shots, and a second rifle is cheap insurance if one gets knocked about in transit, which does happen. The trade-off is more paperwork and more to carry.
So my honest steer: if you shoot the .375 well and don't mind the recoil, take the one and keep it simple — that's what I'd do for a buffalo-led wilderness hunt like this. If the recoil wears on you over a long trip, bring the pair and take the plains game with the lighter one. Either way, buffalo comes down to placement and a steady nerve far more than calibre — the .375 gives you nothing to apologise for.
One practical note whichever way you go: check the outfitter keeps a spare rifle in camp. A knocked scope on day one is the one thing that unravels a single-rifle plan, and most good camps keep a backup .375 or .458 on hand.
