The mathematical probability of hitting 2 blocks in the 99th cumitive distribution factor is astronomical, roughly the same as hitting 2 at <1, not quite the same as the 99th is infinite since 100% can never be achieved.
I'm not really sure what you mean, but by definition the lower tail 0.99 CDF occurs when an event is expected to occur one time in 100.
If that's for one block, it will require total work of 4.60517 times the network difficulty. If it's for two blocks, it will require total work of 6.638352 times the network difficulty.
In the first case we would expect this to happen once in one hundred blocks; in the second case once in two hundred blocks.
That's not even close to infinite.
Actually it is multiplicative not additive. Thus it is one in 10,000. Which if you extrapilate out at the same difficulty means it should happen about once in 25 months. I.E. hardly a once in the life of the universe event.