how do I update a list to overwrite duplicates with new data
 

I have a list of horses and each week I want to update their race entries
with keys for the races. I. E. column B might be "1" according to my own
key. Column 2 could be "T"
I copy and paste from a scanner into the bottom of the worksheet and place
the "key" letter next to the new entries say in this case the key is "4" in
column B indocating a new race/ entry. I then sort in alphaabetical order.
All the horses are now sorted but if a horse has already "1" and "T" then "4"
will show up as a duplicate and not against the original horse name..

How do I update the informaion so that dupicates receive the new data but
are not shown as duplicates as I have to go through the list deleting.