IWDC -invitation problem

My colleague tried to invite me:

He set an event to his own calendar and set me as attendee (direct at Icewarps webclient at our own server)
I received an email and opened this with the IWDC.
I accepted the event and sent the answer message
At the email view the information switched now to “you have accepted this invitation”

So far so good…but the problem is:

Now I’ve two events at my calendar for this (same) event
one with the state “accepted”
one with the state “-”
and my invitation list at calendar view increased to 12…

What’s wrong?

can you please send us (staron@emclient.com) saved event so we can try to simulate the issue?

Now I know what’s wrong.
After I received the invitation I accpted it. Now at my calendar I found the entry as accepted and also I found a open second entry for that event.
What was wrong? The current colour scheme of the emClient… I’ve the calendar of my colleague enabled as shared one and with a different colour. But the not highlighted colour of his calendar matches my own colour.
So I thought it’s a second entry for me.
And after he read my answer mail the server alternates the second entry also to accepted for him - so I found the mistake today.

Sorry and forget it.