Hi,
I found same problem in your try demo also, and I found that the root cause was come from the service broker part, but I'm not sure it's because the standard behavior of service broker or because the dropping step is not complete in change notification component.
The following are my test plan to simulate the problem:
1) Open demo apps and connect change notification.
(Service broker named: SDAC_NS_52_QUEUE & SDAC_NS_52 was created.) and test inserting data into dbo.DEPT, everything works fine.
2) Disconnect connection
#1, and reconnect again
(system get back same SPID, so the service broker name will be same) and test inserting data into dbo.DEPT, now the transaction to service broker queue will be double up become
2 transaction inserted.
3) Repeat test steps
#2,
(because I'm the only 1 user for this DB so SPID will be remain, and at this moment service broker name will also remain) and the queue transaction will be increase
+1 every-time I disconnect and reconnect.
Testing solution: 
I try to change the service broker name generate steps to make sure every time when system generate service broker with unique name, the problem had been resolved.
May need your clarify are my solution is a correct way to resolve it.
Thank you.
, I found this because I wan to play sound when data changed, so I put my coding in "TMSChangeNotification.OnChange" but it keep on sound me more than 1 time even I only change 1 data.
