I once bought a couple of somewhat rare TSR Modules from a seller who was selling a bunch of them at the same time.
I think my wins were one R Series Module and an RPGA series module.
Anyway, Seller shipped the wrong package to me and shipped my items to the guy that SHOULD have gotten the stuff I got.
Anyway long story short, the seller told us he would pay shipping to each of us if we agreed to ship our packages to the rightful new owners.
We did and everything came out OK.
That was like 5 years ago and I have not had that sort of thing happen to me as a buyer again (thankfully).
Now to the present time.
I recently sold a few items (about 20 or so, and still selling a few) and as a guy who almost never sells my stuff (I MUCH prefer to trade) I am still (after many years on E-Bay) admittedly a rookie seller compared to many folks here.
I had a lot of the those recent listings end at nearly the same time and packaged them all in one day to ship on the next non-postal holiday.
Yeah, you know what's coming don't you?
I mistakenly sent one buyer TWO packages when he should only have been sent one.
Long story short, the person who got the extra package let me know immediately and even offered (without my asking) to send it forward to the correct address for me.
Of course I let the true new owner know of my screw up and sent more than enough funds to the nice guy who sent the package forward.
Both guys gave me good feedback too....
I am one lucky (though somewhat stupid) seller.
I am also VERY happy that both buyers got the items they had paid for.