In this instance i think the OP was wrong to keep the 2nd chair.
I myself had something happen with Amazon.co.uk a few months ago....
ordered some DVD-Audio discs, as i was taking a week off work the following week and as it was thursday i opted for 1st class post (next day delivery after dispatch) to make sure i got them for my week off.
Well, a whole week came and went, so i emailed Amazon, who said they would look into it, they emailed back quickly, said they couldnt find them their end so out of goodwill they will send me the package again no extra charge.
The package dispatched a day later, the following day to that a package turns up at my house...turns out to be the original! so i email amazon and tell them, they email back saying once the second package turns up to return one of the to the address supplied blah blah.
So the second one turns up within another day. Quickly i just like to say i think that was very good of them to act so quickly and decently.
Only problem is, 2 months on and i keep forgetting to post the other one back...lol. I havent even opened the package so i havnt used anything i shouldnt be. Im just terrible when it comes to things like posting letters or parcels, really terrible. I would feel bad if i opened it up and say sold on the items, but i just cant get round to posting the damn thing...lol. So i dont feel bad, and i dont think i've been bad as such as these arnt items that will deteriorate with time or become outmoded, i will eventually do it, i promise, if only because Amazon acted so swiftly and nicely.
edit: btw, im not looking for salvation from the posters of AT...just to clear that up, i wrote all that cuz im at work and bored senseless and it passed some time....hehe