Uscis case status showing as "Duplivate notice was mailed"

[alex4]

I recieved noir in 2014 and it got updated on Jan 15,2015 and he status showed as

On January , 2016, we stopped the revocation or cancellation of your Form I129, PETITION FOR A NONIMMIGRANT WORKER, Receipt Number

But on Feb ,2016 it again changed to the status as shown below which is very weird

"On February ,2016, we sent you a duplicate notice about a decision on your Form I129, PETITION FOR A NONIMMIGRANT WORKER, Receipt Number "

Please help me what does this mean??