Here's one way to do it.
1. Make a backup of your data so you have a fallback position in case
something goes horribly wrong.
2. Suppose your data is set up like this: Name in column A, Address in
Column B, City State Zip in column C, phone number in D. Alpha sort
column A so the names are in alphabetical order.
3. Insert a new column B so that column B is blank and addresses are
in col C.
4. In cell B2 (assuming this is the second address in your list) enter
the formula
=IF(A2=A1,"xxxxx","")
This checks the current entry to see if it matches the previous entry,
and marks it with xxxxx when it matches.
5. Copy column B and paste it over itself as values.
6. Alpha sort column B and delete all rows with xxxxx in column B.
7. Alpha sort the remainder on column A.