There are millions of addresses and there was never a collision and there never will be if mathematics about it hold up. Checking for couple of numbers (even a million is considered a couple of numbers) is unreasonable to say the least. Chances are just so low, that you might as well not waste your time or start worrying for all the more likely things to happen, like getting hit by a lightning a thousand times in a row.

Humans are just not good at understanding such huge numbers so people naturally worry about address collisions and similar stupid things.
Don't worry, your key will not be in the first or the last million keys. It is simply not going to happen if your random number generator is any good.