Why I have three rear derailleurs

There were only four of us on a "training ride" three weeks back.  One guy was about the same level as me, the other two are really strong guys.  So as we're starting up another hill about an hour into the ride, I shift into the big ring to catch up and promptly drop my chain.  It fell off on the outside, towards my pedal.  I shifted back, hoping to pull my chain back onto the ring (it's worked a couple of times), but it didn't this time.  I felt the chain catch, or I should say lock up.  I tried to force it a bit (just a bit), and then I felt the whole bike lock up.  Fortunately, by this time, I had lost a considerable amount of momentum and the bike was almost to a stop.  The wet pavement helped me from doing further damage to my drivetrain.  I pulled over and noticed my rear derailleur in my rear spokes.  Not good, not good at all.  Worse, the other guys were over the hill and gone, and I didn't have anyone's phone number with me.  So I pulled over and tried to get the bike rideable.  Did I mention that it was cold, like mid-30's?  And windy?  And the sweat in my gear was starting to make me shiver?

I was about to call home and get my wife to come get me (it would have taken her an hour plus) when my ride mates came back over the hill looking for me.  Chris Moore was able to get me one gear, one stinking gear, but that was enough to ride on, and we took off.  My one gear was 53x13 or 14, I forget.  And the derailleur hanger was at a 45 degree angle, so the derailleur pulleys were out of alignment with the chain, meaning a huge amount of drag (Chris said it felt like 50 watts, I have no clue).  It felt very tall.  Well, we went back the next 16 miles to the shop.  The whole way I can't shift.  I can't accelerate worth a flip and I don't want to stop.  At the shop, the wrench (a guy I trust a great deal, despite his misdiagnosis) informs me that, now that he's worked the derailleur hanger back, the derailleur itself is bent.  Time for a new one.  Oh, new ones cost $100.  And it's right before Christmas and with six kids, I'm pretty much broke.  So much for finishing off those last 120 miles to get to 2500 for the year...  So I did what any other near-broke cyclist would do, I went to eBay.  I put the bike in the shop, it needed a new chain anyway, and I told the guy "I'll provide the derailleur and the hanger." I spent the rest of the week looking on eBay.  Meanwhile, another wrench at another shop who's a pretty good friend (I'd buy him lunch on his birthday kind of buddy) says, "Hey, maybe I can find something at home to help you out."  Of course, I'm impatient, so after a couple of days of no news from him, I found a nice Ultegra 9 sp rear der, which would work with my 10 speed system per Shimano, and I bought it the Friday before Christmas.  Then I wait and wait.  I bought it on a Friday.  The following Thursday, I ping the eBay seller.  No response.  I ping him again on Friday, he says "Your der is on its way."  Ouch, no way it will be here before the big ride on New Year's.  Sat night, my buddy at the shop says, I've got a better der, Dura Ace, and it's yours for $5 more than the eBay der, and it's ready tomorrow.  Rock and roll!  The eBay one will be a backup.  So I buy it, take it back to the shop my bike is waiting at (same franchise), and get everything set up.  I picked it up today, but the guy tells me that the "broken" der isn't really bent.  It must have been the hanger.  Dang it, I had that the whole time!  I ordered a spare when Joseph bent one last Summer.  Then I get home, and guess what's in my mailbox?  The eBay der!!  So now I have a 9 speed Ultegra, a 10 speed Ultegra, and a 9 speed Dura Ace, with the last one installed.  Yuck, now I have to go back to try to sell one to make back some change.