Answer
The 2nd source [with $10^{-6} W/m^{2}$ intensity] has more power and by 1000 times.
Work Step by Step
Intensity of 1st source = $10^{-9}W/m^{2}$
Intensity of 2nd source = $10^{-6}W/m^{2}$
$Intensity = \frac{P}{Area}$
Area being same, Intensity is proportional to power of the source.
So, the 2nd source has more power and by 1000 times.
