ZBW controller described a very confused coordination event when an adjacent sector's communications regarding a descent limitation was directed to both the RADAR and D-Side controllers; resulting in incomplete communications.

Narrative

Air Carrier X was handed off to Sector 31 at FL360. Sector 31 called the RADAR Controller at CAPE and told him to descend Air Carrier X to FL340. (Sector 31 had already accepted a hand off on Air Carrier X and had control of the data block). Sector 31 D-Side called me (CAPE D-Side) and told me to 'disregard the descent on Air Carrier X' I had no idea what he was talking about; I asked him to repeat it and he told me to 'disregard the descent on Air Carrier X'. I looked and saw a hard altitude of 360 in the data block so thought that he was telling me that they were not descending the Air Carrier X. The CAPE Sector had already descended the aircraft to FL340!!! I had no idea since they had PREVIOUSLY called the CAPE R-Side to initiate the descent. Luckily; my RADAR Controller saw my quizzical look; stopped the Air Carrier X from continuing his descent. Recommendation; this is an ongoing problem with Sector 31 and 46. Their D-Side calls the CAPE Sector D-Side and places us in the midst of incomplete coordination. Why in the world would you call Controller A (CAPE RADAR) and tell him to descend an aircraft (that you have track control of) and then call Controller B and tell him 'disregard the descent' and think that the coordination was complete; poor training and technique. Keep RADAR functions directed to the RADAR Controller---do NOT call the D-Side with incomplete coordination and/or control instructions.