SQL Server 2000 offers a function called CHECKSUM. The main purpose for this function is to create what are called hash indices. A hash indices is an index built on a column that stores the checksum of the data found in another column in the table. The CHECKSUM function takes data from another column and creates a checksum value. In other words, the CHECKSUM function is used to create a mostly unique value that represents other data in your table. In most cases, the CHECKSUM value will be much smaller than the actual value. For the most part, checksum values are unique, but this is not guaranteed. It is possible that two slightly different values may produce the same identical CHECKSUM value.
With regards to the above, does anyone know in what circumstances two different values would return the same checksum value?

I'm looking for something that will generate a unique hash for variations of customer records.

I definitely would not want the same hash to be generated in the following example:

John Doe
123 somewhere

Jon Doe
123 somwhere


Thanks in advance,