2 exact same vape devices have different airflow, why is this?

Hey all, I own 2 smok stick v8 baby devices and I'm really puzzled as to why 1 has a tighter airflow then the other. Both same device, both airflow open wide, both same coil. Both same <a href="http://www.vapininthecape.com/eliquid_c_7.html”>juice. It's really bugging me. Any1 had similar issues? Cheers.

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