I never thought of that. Generating the same address as someone else. Is that theoretically possible?
That depends on what you mean by "theoretically possible".
If the address is generate in a truly random way (as it should be), then it isn't
possible by any reasonable sense of the word.
For example, all the air molecules are randomly moving around the room you are in. As such, any configuration of those molecules is "theoretically" possible. Perhaps the molecules will all randomly end up bunched up in one corner of the room, and you will suffocate. It's never going to happen, but would you consider that to be "theoretically possible"? Most reasonable people would not consider it possible at all and wouldn't spend any thought power on worrying about it.
Or is there a mechanism in place to ensure that never happens?
The only "mechanism" is the EXTREME odds against it as long as the addresses are generated randomly. If you use some non-random system to generate an address, then it becomes possible that someone else could figure out the same non-random system and generate the same address.
I know that the odds make it almost impossible.
Not "almost" impossible. The odds make it
impossible. (by any reasonable use of the word as long as the addresses are generated in a truly random way).
That's exactly what I was wondering. Thanks.