Highlight Date

Check this one:

Formula:

=SUM(IFERROR(SUMPRODUCT(((LEN(B1)-LEN(SUBSTITUTE(B1,$G$1:$G$32,"")))/LEN($G$1:$G$32))),"")-SUMPRODUCT(--ISNUMBER(SEARCH(Before!$G$1:$G$32,$B1))))

= 0 - no duplicates
> 0 - number of duplicates in a single cell
I checked only a few cells because I'm too lazy