Thank you for all your usefull infos, will help me a lot. I talked to him and he said that i can open the box to check it. Now, can you tell me what to check to be sure that the purchase is safe?
Also, if its stolen, what can happen? I read that Apple has no database for SNs to track them.
With the warranty, youre right , its strange that it isnt used for 2 years...but there a lot of new MBP mid 2015 on the internet.
Thank you again.
PS: I found that the part number is like that because its a custom configuration (512gb) and apple gave to these custom configs unique family ids.
With regards to the warranty, what have they said is the reason? Always look out for "I'm selling it for a friend". I suppose it's feasible that there could be a few, I think maybe unsold units sit in warehouses and eventually trickle down to 3rd party sellers who buy them in bulk for cheap. But I can't imagine there's many people willing to shell out €3000 on a computer and just do nothing at all with it.
There's not much you can do at the point of sale to check it's safe, often these are rushed scenarios and nobody wants to be standing around for 30mins whilst you check every nook and cranny.
If at all possible, the simplest safe thing is make sure you're meeting at the sellers home address. As it's unlikely they'd scam you when you know where they live. Normally what you'd do is turn it on and firstly check (If it still had a login) that the name corresponds with the seller in some way, and check that the serial number in 'About this Mac' is the same as the one on the box. But assuming it is brand new in box it won't have any charge and you won't want to stand there and go through setup. So again use judgement.
I'll give you worst case on what could happen, not to scare you but so you can make a better judgement call.
If it was stolen, a few things could happen. Firstly you could be charged with handling stolen goods which is usually a serious offence in any nation. Secondly if the original owner has registered it stolen, there are ways to track it though 'Find my Mac' or other means, and you would be forced to give up the computer (Loose your money). Thirdly the seller themselves can report the device stolen and claim you stole it.
If you were buying through eBay or something you at least have protection, but I'm assuming you are paying cash. Make sure you get a written receipt with the sellers address and signature on it so in any worse case scenario you have some proof that you purchased it.
Now that all sounds like overkill and it completely is. But any genuine seller will have no problem with writing a quick receipt for you or letting you inspect a device, after all you're spending €1300 and want peace of mind. It's when you ask sellers to do these things and they make excuses is when you just walk away, it's not worth the gamble.