How to assign a number value to text within worksheet

I need to count the number of times a value appears in a row and assign a number that tells which occurence of the text it is.
For example

Name Address
Jim 123 Smith Street
Jane 123 Smith Street
Bob 543 Apple Street
Mary 543 Apple Street

I would like a way to insert a column that puts a 1 next to Jim and a 2 next to Jane, a 1 next to Bob and a 2 next to Mary and so on.
Ultimately, I want to sort the list and delete all the twos, thus deleting the duplicate address entry.
Thank you