I receive two Google Calendar invites for ADPList Group Session events. It doesn't matter if I accept or decline; they will "refresh" at some point, and the meeting on the calendar (in Google Calendar and Apple Calendar) will look as if I just received it and hadn't accepted/declined. I'll also keep getting notifications as if it's a new invite that I haven't responded to. I like to keep a clean calendar, and it frustrates me to no end!