You'll find that none of Excel's tools (Sort, Pivot Tables, Database
functions, Subtotals, Charts, Autofilter, Advanced filter, Data form, to
name a few), work with multiline records. I think you should look strongly
at converting your data to a bona fide database-style table. It will open
up all kinds of Excel functionality.
This is a simple way to find the duplicates:
=SUMPRODUCT(--((A1&CHAR(1)&A2&CHAR(1)&A3&CHAR(1)&A4)=($A$1:$A$200&CHAR(1)&$A$2:$A$201&CHAR(1)&$A$3:$A$202&CHAR(1)&$A$4:$A$203)))>1
The formula concatenate 4 rows and tries to find a match.
CHAR(1) prevents Errors like ABCD&""&""&""=A&B&C&D