As a buyer...
You can only open 1 VALID dispute against the seller.
If you, the buyer, try to open a 2nd or 3rd dispute you can but it will automatically be closed by Paypal after you open it.
As in your case the first dispute for Non-Receipt was the VALID dispute.
Once the tracking number checked out then Paypal closed the dispute in your favor.
Then it looks like the buyer did not like what they got....
So they tried to open a 2nd dispute for Item Not As Described.
Then Paypal saw that it was the 2nd dispute over the same item and closed the dispute within about 1-10 minutes after it was opened.
You won that dispute also.
Personally I love it when a buyer opens a Non-Receipt dispute because I KNOW they will lose it.
And then they can not open another VALID dispute over the same item.
I actually had a buyer open a non-received dispute. I provided the tracking number, and later he received the item. Somehow, he was able to then up it to a item not as described. I, as always, simply agreed to refund, as long as item was returned...
You are probably correct. He opened a dispute for not received. Then turned it into a claim. Somehow, though, he did change it from a not received to a not described. The weird thing was when it first went to claim status, it was for not received. Several days later, it changed to not received....