Which turntable to keep?

I have both in my TT collection. That's a tough choice to make! 

Good question!  Personally, I have always been partial to a Dual and frankly I think it is a better TT than the Miracord.  On eBay, you can get almost twice as much for the Dual as the Miracord, so clearly a lot of folks think so as well, and there is a message there.

Another option, and a better option besides, is selling both, adding some pennies, and buying a better TT.  Most of the TT's in the $500 to $700 price range are significantly better than either of these vintage units. The Dual is a cool, vintage unit, but if it was my system, I'd sell both and upgrade.

You didn't mention what cartridge you have on them and that is a significant issue as well.  

Upgrade and toss the old ones!

If no sentimental value for either, sell both and upgrade. If should keep one that could be Dual, better player and easier to find spares if needed.

I’d keep the Dual. It’s better than some of what you might upgrade to.