Pool hashrate question?

I have 2 computers mining for me one is showing a combined hashrate of ~560 and another one ~40, in total I should be reporting ~600H/s but my flypool account hovers at around 550. I know that it uses vardiff but it is normal for my hashrate to be THIS much lower than reported?

http://zcash.flypool.org/miners/t1eyHhYY2vTKRb5wgUyj1P3tmYDSAYNDMPb

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