Could be for a couple of reasons. Parallel power reduces noise, can give you current division or redundancy. Current division allows each individual conductor to carry less of the current and still supply the total you need. It means you can use smaller wires or have lower loss (loss or voltage drop is proportional to current in the wire).
Keep in mind that you need to size and/or fuse each individual wire so that it can safely still handle the load. Say you have a 100A load on two wires that are each too small to handle 100A but the wires can take 50A. Don't run a single 100A fuses that branches to two conductors, you need to run (for example) a 50A fuse on each conductor.