When you first get your hands on your new belay, you may notice that it has two holes. From the get-go, you may be confused to why the manufacturer integrated this design element into the device. No, it is not for aesthetics. Instead, it does have a use. In some instances, these devices are made individually, so the two holes provide a different amount of friction when in use. In other cases, you may want to climb with two lines of anchors.
If so, the two holes play a crucial role as they make it incredibly easier to belay a two-rope climb. Of course, the two holes can also be utilized if you want to loop a rope around an anchor and to place it through each eyelet. However, if you are not obligated to use both holes, then you do not have to.