Hands down, I'd splash out for the best tripod I could possibly afford (XFR is offering a b@da$$ Miller that looks practically new for an awesome price right now in
Trade & Exchange) before going for a second camera (and I daresay most of the experienced 'narrative filmmaking' style shooters here would concur). Skateboard wheels, plywood and PVC pipe can yield dolly shots which are all but indistinguishable from high-end pro gear, but the only way to get professional-looking tilts and pans (which you'll probably need more than twice as often) is to suck it up and buy a nice fluid head!
I've worked on a few multi-cam narrative projects, and there are some very sound reasons to have two cameras: a "back-up body" on the truck can save a shoot when your "A" camera goes down, a small second-unit can go out to shoot pickups and inserts on the "B" cam if the production falls behind schedule, and of course multiple coverage of big stunts, crowd scenes, pyro FX and any other scenes which would be expensive, difficult or impossible restage.
However I gotta also say even when you have a skilled professional operator with years of experience for each camera, the savings in production time is minimal, the additional post time logging and cutting double footage for each take is massive, it makes the director's job much more difficult, and the final result is often compromised in terms of lighting, camera movement and placement, etc. compared to if you'd been able to place your lights, sound boom,
et al for the maximum benefit of one camera.
Unless you really know what you're doing (for example, Ridley Scott nearly always shoots with two, three or even four cams rolling simultaneously these days; but then, he's Ridley Scott, and you're not ...

), IMHO adding a second camera is likely to make your process
less efficient, not
more.