Which Multimeter is correct?
Neither one is probably very accurate if they are inexpensive handheld 
multimeters. 

Perhaps the battery is low or the probe sockets are loose on the one that is varying. 

You can consult the manuals for your meters to know what the accuracy was when the meters were manufactured. A typical accuracy spec on an ohms range for a cheap DMM might be 0.8% + 3 counts, but you might have to short the probes and subtract off the ohms read to get that accuracy on the lowest ohms range. For example, if you short the probes and the meter reads 0.3 ohms, then a reading of 10.2 ohms on the display would be more like 9.9 ohms in reality. 

Better meters will tend to hold their calibration longer. I have a Fluke handheld that is still within spec on the voltage and ohm ranges after more than 25 years.