I have data in List where there is a filed TAG Number and contains numbers like

0405-115560
0405-115588
0304-100560
0304-152560
.....like wise

I want to now find out if all the numbers are unique and that there is no
dulicate number in this field.

There are around 600 to 1500 rows of data in a list.

Can I have a clue to get over this problem ?

Thx
Shanks