Yes you can split them, for sure.

Star at the root, and decide exactly where you want the split to be. You should ALWAYS start at the root, cos if you start at the tip, you may very well end-up with roots that aren't properly defined and cause you pain. So yes...start at the root and decide exactly where you want the split to be, and carefully section-off the root with a comb. Then, you need to split the actual dread. If your dreads are stiull young, you can sometimes just rip them, or separate the two sections by hand. If you can't do this, get yourself a razor blade/stanley knife/box cutters and carefully slice down the middle of the dread to create two separate dreads. This will undoubtedly cause some hairs to be cu, but you can bind them with yarm/cotton/fabric strips to get em dreading-in and not falling-out...best chance is to manage to do the split b hand, where you don;t get as much damage to individual hairs :)) Good luck!