Two Turntables? Why


OK, been thinking about this for a bit.  Why do people own two turntables?  OK, I understand some traditional uses for a 2nd turntable.  One that is just for 78's, for example.  You may be on a journey to a set up you really enjoy listening to.  You may have even gone the route of an external power supply, isolators, base, phono PreAmp.  All of the accouterments you enjoy because, well, you enjoy records.  But if you are enjoying your LPs and you have purchased a turntable, cartridge and potentially a tonearm that you really enjoy, why do you need a 2nd turntable?  

If you go through all that effort and fun to get to a sound and system that makes you happy, and many of us have, why do it for two or more turntables.  You got a good one, why do you need a 2nd?  Maybe you play all your old LPs from High School on one standard turntable and play all your MoFi and QRP copies on the better machine.  I don't know. 

So, those of you who own more than one turntable, please let me know why you have more than one.  Let me know your thinking.  I'm curious.

Thanks 
pgaulke60
First they are days when you are not ready to get up right away at the end of the record  here the semi automatic .forget the audiophile myths there are some very good ones out.
After a while in this journey some of us find out the best  way to clean our minds from the false claims out there  in the reviews and the audiophile circles is to  listen to  different pieces of audio in our own system  .I enjoy putting the Davids of yesterday  next to the Expensive Goliaths of today
I have  2 modest TT,Rega P3, Thorens TD 166 Mk II, I keep one as spare, back-up, just in case of a fault in the other that would require expert repair. And swap them periodically to evaluate the differences, and as a change of scenery. I don't play 45's or 78's, and no mono either. Those who collect such, I can readily understand, having more arms, or decks. Not hard to understand that, is it?
I also have four systems and four turntables.  Some systems are SS and some tube.  Some have separate phono pre and some use the integrated amp's own phono stage.  Different cartridges are also used and switched out.  I have $20K turntables and I have a $700 Sony digitizing usb table. I guess what I'm trying to say is that different music played on different systems is part of what makes this hobby so involving (and, yes, expensive). But I do not mock the OP for the question.  It is a legitimate question and I have tried to provide an honest response.