I wasn't able to find anything in excel that would accomplish this. I had
the same problem and bought DIGDB and excel add in. I couldn't live
without, it is a wonderful tool to use in exel.
I use the following formula in a list to find duplicates. It doesn't auto
delete but helps you detect easily. Of course you need to ensure your list
is sorted alphabetically and then the formula looks above and below a line
for duplicate: