A GUID (globally unique identifier) is a 32 character
hexadecimal string: If you randomly generate 2, the chance of
them being the same is incredibly small. But what if you
generate 1,000,000, what are the chances there is 1 or more
duplicates in those 1,000,000? What about 10,000,000, or
100,000,000 or even 1 billion? Each new GUID has a chance to
match all those previously inserted into the set. Thanks to
Rawlings answer we have the following graphs: