Finding/Highlighting Duplicates in a Column in Excel to Filter duplicate Rows.

	C	D	E	F
RowNum	colWithDuplicate	Formula1	Formula2.1	Formula2.2
5	14	dup	TRUE	duplicate
6	14	dup	TRUE	duplicate
7	14	dup	FALSE	duplicate
8	17		FALSE
9	18	dup	TRUE	duplicate
10	18	dup	FALSE	duplicate
11	20		FALSE
12	21		FALSE
13	22		FALSE
14	23		FALSE
15	24		FALSE
16	25	dup	TRUE	duplicate
17	25	dup	FALSE	duplicate
18	26		FALSE
19	33		FALSE
20	52		FALSE
21	54	dup	TRUE	duplicate
22	54	dup	FALSE	duplicate

You could use below formula in column D

=IF(OR(C5=C6,AND(C5=C4)),"dup","")

or use below 2 formulas in conjuction

column E
=C5=C6

and

Column F

=IF(OR(E5=TRUE,AND(E4=TRUE,E5=FALSE)),"duplicate","")