Let's see if I can explain this. I have the following rows and columns

Ship Date BOL# PO#
9/14/06 110011 44754
914/06 110011 45451
9/15/06 121114 14541
9/15/06 110011 22412

As you will notice, rows 1,2,and 4 have the same BOL# but row 4 has a
different ship date than 1 and 2. I need to be able to identify when a
single BOL# has multiple ship dates. Keep in mind that my spreadsheet could
have over 1000 lines in it so sorting and looking for it isn't a reasonable
option. I need to be able to either have the ship date change to the
earliest of dates listed, or at the very least highlight the occurances. Is
there anyway to do this? Thank you in advance.