Dale G wrote...
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Notice the first cell shows -0 instead of OT? . . .
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Probably there's a slight difference between the first 2 cells, e.g.,
one contains 5:33:02 and the other 5:33:07. Try

=IF(COUNT(C3:D3)=2,TEXT(ROUND((D3-C3)*1440,0),"+0;-0;""OT"""),"")