afaik, this is not possible.
addresses are never duplicated, that's the whole thing about bitcoin algos and p2p - period.
unless you were actually controlling a remote pc holding one of the addresses on it, there is no way in hell you'd ever see random donations/transfers

That is incorrect. There is no network validation of addresses. They are completely "random" by the node who generated them. There is a very non-0 chance that two nodes can generate the same address, and nobody would be none the wiser.
taking this as constructive criticism, let's say your quote was the case (Could be, or may not be - I'm not saying anyone is wrong)
A good example would be the only one I can currently think of. If I (person A) were to generate a new address, and person B (in another state or country), were to already have this address, and a bitcoin transaction was made to the address, would the end result be double of what the original transaction was?
If so, I was trying to point out that bitcoin addresses take a long time to generate and hence that,
I figured it would check the network if the address was already validated or not.
Sorry, I wasn't trying to be a critic... just trying to answer some questions

It's not that the money is duplicated, but rather that two people now have access to it. Much like, if you have a joint checking account with your partner. Just because you both might have your own ATM cards, and you each go to the ATM and see an account balance of $100, that doesn't mean you EACH have $100. It's kinda a first come first serve access to that money.
The same applies here. If a collision did occur, the person who spent that money first would effectively steal it from the other person. This does not create double spending.
If a system did exist to allow Bitcoin clients to verify if an address already existed, what would stop a malicious user from ignoring this message and just preceding with their newly minted address as their own?