How are these two equations equal: (one interpreted as area and the other length)

2integral{-1 to 1} sqrt[1-x^2]dx and integral{-1 to 1} 1/sqrt[1-x^2]dx

First I understand that the second equation if a circle of radius 1 centered at the origin...and the first equation I'm considering the semicircle int he half plane...but why would they be equal? If I remove the 2 infront of the first integral, would it be the area of the other's region? confused!