I tried to reproduce this behavior in 2.1.0.9 with the sample below, but could not. The CurrentCellChanged event did not get raised, and renderer.NotifyCurrentCellChanging was not hit when you pasted. They both were only hit when you typed into the cell.
Does this sample work for you? (If you get a syntax error when you try to compile it with 1.6.1.6, just comment out the lines with the errors.)
AddNew_3765.zip