Fuzzy matching using T-SQL

I have a table Persons with personaldata and so on. There are lots of columns but the once of interest here are: addressindex, lastname and firstname where addressindex is a unique address drilled down to the door of the apartment.So if I have 'like below' two persons with the lastname and one the firstnames are the same they are most likely duplicates.

I need a way to list these duplicates.

tabledata:personid     1firstname    "Carl"lastname     "Anderson"addressindex 1personid     2firstname    "Carl Peter"lastname     "Anderson"addressindex 1

I know how do this if I were to match exactly on all columns but I need fuzzy match to do the trick with (from the above example) a result like:

Row     personid      addressindex     lastname     firstname1       2             1                Anderson     Carl Peter2       1             1                Anderson     Carl.....

Any hints on how to solve this in a good way?