ZBW controller described confused communications event when a same company aircraft with similar four digit flight number incorrectly changed frequency and was given unexpected vectors by adjacent facility; reporter suggesting company revise flight numbering procedure.

Narrative

I was working RADAR at Sector 47/34 (BOSOX/Providence). I was working a string of arrivals into Boston. The problem began when I switched ACR XXYZ to Boston Approach. ACR XXWZ had checked on shortly before. I still think that ACR XXYZ took the clearance to Boston Approach. About two minutes later I notice that ACR XXWZ was not on course and I questioned the aircraft; no reply. I called again; no reply. At this point ACR XXWZ went from a 080 heading to about a 010 heading. I had aircraft in trail of ACR XXWZ so I took action to descend the trailing aircraft because I was unsure of what the ACR XXWZ was doing. I then called Sector 19; who owns the airspace that ACR XXWZ and the trailing aircraft and advised them of the situation. At this point ACR XXYZ called me and asked what he/she was supposed to do; he/she was past INNDY (STAR fix) and wanted to know where to go. At this point I advised the aircraft to contact Boston Approach; and immediately attempted to call Boston Approach and tell them they had the wrong aircraft. He switched the ACR XXWZ back to me and everything turned out fine after that. Recommendation; the real problem is that ACR XXWZ and ACR XXYZ were scheduled to arrive at Boston within 10 minutes of each other and had the exact same route from RAALF..PVD.ORW3.BOS. The airlines need to change the way the create their flight numbers.