I figured out the double-enter problem. The SUT had the following things set in System Preferences–>Sharing:
[list]Screen Sharing: On
Under Computer Settings, both checkboxes were checked.[/list:u]
Turning all this off fixed the double-enter problem. The lowercase “d” problem is still there, however. Haven’t seen a backtick yet.
Update: I just saw the backtick happen again.