Should a six wire stepper motor not have two coils that are separate from each other?
Looks to me like the commons are tied together and it looks (from the numbers) like you have a particularly crummy meter that probably reads almost 2 ohms with the leads shorted. 

That would explain the numbers if you subtract ~2 ohms from each measurement and the stepper is a conventional 6-wire unipolar stepper with 10\$\Omega\$ coils. As below from here, but with two wires connected to the common. 



Tying the commons together is not a problem since they're normally connected together anyway. A possibility would be that they are tied together because there is an internal thermal cutout in series.