What does the red label say (on the hub)?

Now that you're stuck with the used set, use it AND have the other rebuilt at your convenience. It's never a bad thing to have a backup wheel. You never know when a spoke may break on either set. If the old hub is rebuilt by a good builder and decent rim, it may last forever.

If the old hub is a good hub, heck you can have it repacked with new bearings and grease for about $20. That would make it nearly good as new!

It's not really a bad deal because some will say that the wheel with fewer spokes are faster.