You could do it with a formula in another column, but a simple
solution is to use conditional formatting:
Select cell A2
Select Format/Conditional Formatting...
Change condition to Formula
Type formula as =a1=a2
Change format (maybe using pattern and making it red would stand out
for you)
Use the format painter to add that formula to the rest of the values

On Jan 24, 2:38 pm, Bob Aloisi
wrote:
Hello, I've got an Excel spreadsheet with a single column. The cells
contain a date & time (m/d/yyyy h:mm:ss). I'd like to compare the value in
cell A2 to A1, then A3 to A2, A4 to A3, etc. to determine if it's a
"duplicate" or "different".

Can you help?

THANK YOU