Accept while out of office

Hi,
I have a weird Outlook issue. I have set my Out of Office to auto-forward
all mails to my colleague in my absence. I received a meeting request while
away, which, as requested was forwarded to my colleague. He accepted it but
the meeting organiser was then very confused as it did not show that he had
accepted it on my behalf, just that he had accepted her invitation, she was
then very confused as she hadn't invited him. Also, upon him accepting it,
it added to his calendar, not mine! has anyone alse come accross this before?

many thanks

Kerry