Hi Roy,
What do you mean by "the meeting was scheduled at 8:30am at two different calendars"? Do you mean a user scheduled the two meetings from two different accounts?
Please try the steps below to troubleshoot this issue:
1. If you turn on Cached Exchange Mode (CEM) in Outlook, please turn off the CEM.
2. If you separately send a meeting to the two different calendars at the same time, will the user see the correct time?
3. If other users send two meetings to you, will this issue occur?
Thanks,
Edward Qu