That's not even statistics.
That's simply the pigeon hole principle.
A second has 1000ms. If you have more than 1000 users doing things per second, there MUST be a collision.
A second has 1000ms. If you have more than 1000 users doing things per second, there MUST be a collision.
Even with a small number of users per second (like 20) it becomes likely to happen often.
... also, it Technically depends on your throughput (something something queue theory).