If your provider allows SIP Forking (two registered devices, same account, at the same time), then there should be no reason it won't work. You would have the same issues, as registering two sets, one at work and one at home. If one were in use, and your provider only allowed one concurrent call, then an outbound attempt from the other location would fail. Any incoming call would ring both location, but show as a missed call if the other location answered, with no clear indication that that happened? Was it a missed call, or did some some actually pick up. A few things to consider when planning how the trunk routing will be set up at each location.