AFAIK I haven't see anyone create a thread when they create a new wallet, the wallet have been funded (which mean someone have been use this existing wallet).
That can happen only if you use a malicious tool. There have been cases that people got a used pre-generated address from a malicious paper wallet generator.
If your private key is generated randomly, it's impossible that you generate an address that has been generated by someone else before (Of course, in theory that's possible).