How much benefit do you get out of the second system? If the systems have unique advantages, then it may be worth it. For small differences, you may end up just using one.
I have two 5D bodies, one with full-spectrum sensor (5D2), the other is my go-to body (5DsR). Then a 4x5" set-up, completely different. Then a microscope system for images I could not possibly take with an SLR. Then use a scanning electron microscope, again totally different.
I am never confused between SLR, 4x5", micro, and SEM. The biggest confusion is between 5D2 and 5DsR, but they offer unique views, so it is worth it for me. I don't think I would use any lower end dSLRs (6/7/60D etc.). No need for Nikon or m4/3 either. The only one I might considering is a 1D series for fast frame rate.