Don't know if it was just a typo or not. But if you remove the " (double quote char) just before the closing }, it works as expected on my system.
$cat myfile
l1w1,l1w2,l1w3,l1w4,l1w5,l1w6,l1w7,l1w8,l1w9,l1w10
l2w1,l2w2,l2w3,l2w4,l2w5,l2w6,l2w7,l2w8,l2w9,l2w10
becomes
$cat tmpfile
l1w10,l1w5,l1w1,l1w3,l1w4
l2w10,l2w5,l2w1,l2w3,l2w4
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