I created a reply rule for my mailbox. This reply rule is configured to
send a reply if an appointment is recieved. If I schedule meetings and I
am also a participant of these meetings, then I get a reply for every of
my own sent meetings.

This is a little bit confusing.

The reply-behavior is different, if a mail is sent. Then the reply
is only sent once. I think this works as designed (OK fur us).

Do I have a chance to change the reply-behavior for appointments so that
there is only one (if any) reply to myself?

I know - a rule could solve the problem - but is there another way?

thanks in advance