Its accepted. If you are falling in normal ranges it doesn't really matter hugely to be honest. You just have to accept the meter that you think most accurately measures.
Two ways of checking this out:
Somewhere on internet there is a list of the average testing data for machines.
Me, i just do a test at the same time as they take blood out of my arm and compare the fasting glucose to my meter when I get results back from GP.
i have a new pump with a built in meter. The differences on this are minimal when I'm not wound up... I'm wound up at moment and last night I did a comparison.. One odd tester By the same manufacturer said 6.8 (acceptable pre bed) my pump meter said 9.3. I believed the 1st meter and did not give myself a correction dose of insulin. I was right. This morn being less anxious sort of I did a test and both within 0.5 and normal range....
I think it also depends on the blood used. Whether it is direct from pricking finger immediately or whether it is the same blood but the 2nd or 3rd drop from finger.
Its not worth worrying about unless you have instances like me that you need to check (currently) before giving yourself acorrection dose of insulin.
I don't normally do this but because of being so wound up I had to.