I think the problem is that the backup camera you never needed until now will only be needed for the period of time your main body is in the shop. One question that comes to mind is what will happen to the duplicate D7000 used as a backup once your main body is returned all shipshape?
I've been predicting for more than a year and a half that Nikon will release the D300s successor sometime during the April/May 2013 period. Whether that DX body turns out to be the predicted one or a successor to the D7000 instead is anyone's guess and I won't hazard another prediction.
A brand new D7000, with full Nikon warranty, is available now at most authorized dealers for only slightly more money than a refurb or a used body. If someone is going to pitch a 2nd D7000, might as well get a new one then.
On the other hand, if the main D7000 is going to be back from the shop any time in the next month or two, why bother with a 2nd D7000 right now? Instead, it might be worthwhile considering a P7700 enthusiast camera. It's not DX, but image quality is very good, it's got all the manual controls, the lens is excellent, the sensor is the best one Nikon has in its small form factor stable, and the camera handles really well. The P7700 can certainly backup any big body for short periods of time and for non-pro use.
So if anyone is taking votes, I'd go for a P7700, wait for the D7000 to return from TLC, then relegate it to backup position (or sell it) when the new DX body champ shows up in four months or less. The P7700 will remain a great stealth camera and a wonderful small, general purpose camera, and an occasional backup. Or sell the P7700 instead, and keep the freshly laundered older D7000 as a second body with a permanently mounted favorite prime lens or something like that (as well as for use as an occasional backup).
There are some superb and better non-Nikon choices I could recommend instead of the P7700, e.g., a Fujifilm X100 or the newer X100s (if the X100s shows up in stores in the next week or two - if it's not on shelves already). The X-100 series from Fuji has an APS-C/DX sized sensor, superb image quality, fixed prime lens of excellent quality, and the full range of external controls on a tough, serious, well built body that features Fuji's amazing hybrid viewfinder. It's a completely different approach than staying pure Nikon obviously, but it can get a photographer's head into a different design, a slightly different approach to image capture and ergonomics, and extends technical familiarity beyond Nikon (which really isn't necessary, but which also doesn't hurt anything at all).