How did fraudsters combine two different transaction numbers?

[ilan95]

I ordered the goods and paid with PayPal. I received an e-mail message from seller number 1, from e-mail number 1. He gave me transaction number 1. After a while, a parcel arrived at my post office with a different transaction number (2) from an unknown seller. When I received it, then transaction number 1 is marked as received. In what capacity do I need to open a dispute? Either so: I did not receive my order, or so: I received an order that is significantly different?
Why do I need a transaction number if it has a double that cannot be tracked?

[ilan95]

Perhaps I understood the scheme of this fraud. They made their website or used the services of other scammers. On this site, they came up with an internal transaction number for their country, it is not international. It synchronized the international transaction number, BUT they gave me the internal number. When I received the international transaction number, the internal number was marked in the internal site. It all seems simple, but for buyers it is not clear.