Multiple returns from dbus-daemon?

Hi all,

I was just doing some updates to my dbus library, and I noticed that
when I try to remove a match rule that doesn't exist, I get back two
responses from the dbus-daemon: one 'method reply' message and one
'error reply' message.  Both of these messages have the same reply
serial.  Is this to be expected?  The spec says that it makes no
sense:

If the reply has type METHOD_RETURN, the arguments to the reply
message are the return value(s) or "out parameters" of the method
call. If the reply has type ERROR, then an "exception" has been
thrown, and the call fails; no return value will be provided. It makes
no sense to send multiple replies to the same method call.

Is this something specific to dbus-daemon, that it 'returns' twice?

-Robert Middleton