Xi6-T box

Hello I received the xi6-T box for 4k streaming. It said to return equipment but I still have the x1 for DVR. It is hooked up directly to my tv with a cable. Is the xi6-t box just supplemental? Is there a reason to return my x1 box? I am assuming th xi6 doesnt have dvr capabilities so I'm just a bit confused on what equipment xfinity expects me to return