A two into one is for either for data line and phone, which is the most likely reason. While the input is two sets of four wires, only two in each set is active. The single R11 plug will provide phone connect to the phone and the other pair provides data connection to the data line.
How do I connect two coaxial cables?
Quote from Youtube video: Into one side of the capsule. Ensure the copper reaches halfway into the capsule secure the copper in place by re tightening the screws repeat this on the other side with the new coax cable.