If I own one side, (depending on how property is deeded) and I do not want the other guy's equipment on it, good luck. Much will depend on how the property is deeded. Some are "checkerboarded" while others have property line down the middle. If proprty line is down the middle, there will be a trespassing issue. The town can not "make" you do anything. I used to do a lot of work for a utility, and did a lot of work where they would pay to correct an existing situation where there was a trespassing issue. I don't believe that anyone could make the owner of one side give an easement to the other party if he were opposed.
If however, commion area were checkerboarded, one owner would probably be able to install his meter on the other side of the duplex, and pipe around the building to his side. Still might be a code violation if you can't group the 2 disconnects, but inspector might be inclined to overlook it.
I still think this issue is complex at best.
