She has 2 dogs and it takes 20 minutes to groom just 1 dog so it takes her 2*20 = <<2*20=40>>40 minutes per day to groom 2 dogs
In 30 days, she will have spent 30*40 = <<30*40=1200>>1,200 minutes grooming her dogs
There are 60 minutes in an hour so she spends 1200/60 = <<1200/60=20>>20 hours grooming her dogs
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