I have never seen such large anomalies between different meters.
I use two meters, the Accu-Chek Performa and cross check with the Optium Xceed. I have been told by an Accu-Chek rep not to take BGL close to computers because you can get false reading. I have found humidity or moisture contaminated Performa test strips will give abnormally high readings and Optium strips left in the sun or high temperatures to long, giving exceptionally low readings. If I have an unusual reading, I always recheck then cross check with the Optium.
That being said, I also see big differences between the two meters. If I am having a fast falling hypo the Optium will always read lower but if the hypo is slow falling and/ or I have very little insulin on board, both meters will have similar readings. After I have eaten and BGL are rising fast, the Optium reading will be higher. As a Sugar Chemist, I could give an explanation, if sugars, especially glucose, dissolve in the blood and react exactly the same way as they do in water but I no longer have access to a lab to prove my theory. I am now taking BGL with both meters prior and after blood is taken for my 3 monthly blood test and finding a similar trend.