two hubs will not neccessarily test correctly. I have had some strange errors regarding hubs, besides, hubs require a crossover cable for HUB to HUB communication, or a crossover port, two power outlets and desk space - you also have to go to two different locations to check if your drops are good. With a loopback it fits in your toolkit, uses batteries, can be used to test cable drops and jacks, and you can test from one end.