I stand corrected on the single use DVR.. Kinda.. They do allow for shows to be recorded on one and watched on another..
From TiVO.com
Multi-room viewing Having two or more TiVo DVRs connected to your home network gives you two or more times the viewing freedom. Record a show on one TiVo DVR and watch it on another in the house. Start a movie in the living room and finish it in the bedroom!