You should only have one center hose, and that will feed the rear drums. There should be one port on the proportioning valve that feeds the single brake line to the rear, which then connects to the center rear hose that tees off for both rear wheels.

Each front caliper should have its own hose and line, which go to separate ports on the front of the proportioning valve. Nothing the previous owner did is correct. Either he installed the wrong proportioning valve, or something happened with the old setup and this was his "ghetto-rigged" solution.