HABTM: xxx.objects.remove yyy return value question

Hi all

I have a HABTM relationship between partys and organisators.

When I remove party #1 from organisator #1 using
org1.parties.remove(Party.find(1)) then I get the party object as return
value. So far, so good. But when I try to remove the same party again
and again, then I don’t get an error like “This party is not associated
with org1” but always the same party object!
So I can’t find out if the relationship really existed or not. Is this
normal?

Thanks and greetings
Josh