Not in any current version of Outlook AFAIK.

Signature
Milly Staples [MVP - Outlook]
Post all replies to the group to keep the discussion intact. All
unsolicited mail sent to my personal account will be deleted without
reading.
After furious head scratching, brendanb asked:
| I would like to know if it is possible to have a notification or to
| have conflicting appointments or meetings highlighted so that they
| are easily identified and resolved.