How to match information in two columns?

[Guest]

I have received an excel spreadsheet of 120,000 tax warrants for the city I
work in (I work at a bank). I have downloaded our customer database into
excel and need to know how to search for name matches. The customer
spreadsheet contains approx. 20 characters of the customer's name (last,
first, middle initial). How would I perform a search or match? I have never
used any lookup or match functions before. I read the help files but find it
confusing and do not get the results I anticipated. Any help would be great!

 

[Excelenator]

It would be REALLY helpful if you could supply an example of how the
data is presented in each file.

 

[Guest]

Customer Name Tax Warrant Name
Smith Joe Smith Jane
Smith Josephi Smith Josephine
Smith Karen
Tucker Samuel

I need to find out if any of the names on the left exist in the column on
the right, or vice-versa. As you can see, the column on the left contains
the full last name but only a partial first name, depending upon how long the
name is. I thought about trying to match just the first 6 characters of the
last names but cannot figure out how. We are trying to get around actually
sitting at the PC and doing a manual look up on the system. It would take
forever!

Thanks.