Thats means once an account had been created its impossible for anyone to find it twice by random?
A wallet is not an account. A private key is a random number from a hugely big interval. The address is based on the private key.
Now if you leave a proper wallet software generate that number for you, the chance others will generate the same number is smaller than the chance for winning the lottery many times in a row. So it's pretty safe to say nobody else will have the same address.
On the other hand if you pick a nice number like 123456789..... to be your private key, somebody else might easily generate the same wallet and steal your money.
PS. Don't use websites generate your wallet, use wallet on your computer, or, better, hardware wallet.
PPS. What I was telling was about bitcoin. Eth / metamask stuff may or may no follow the same rules, you can ask in the altcoins area.