There are currently 329,993 addresses in the Bitcoin network. Say that this number of addresses are created every day for the next 140 years. That's 16,862,642,300 addresses.
The chance that at least two of those addresses collided is about 9.7x10
-29, using the formula
here.
Calculation.I get that the chance is very, very, very small. But unless there is no chance at all there is still a chance. All I am saying is that there should be a check to make sure that a new address does not exist already.