.. Thus I need to delete one of the data at row 1 or row 3
to get the exact hour for usage of room 101.

Just a clarification that "uniques" are treated as the first occurences from
the top row down in the formula construct. Duplicates would be those
identified further down which have the same "date-time-room" characteristic
as any preceding first occurence lines above it.
--
Max
Singapore
http://savefile.com/projects/236895
xdemechanik
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