yeah, I think your right..
LL=\frac{ln(10^{12})}{0.1}=276.31..
Double Intensity;
L=\frac{ln(10^{12}\times 2)}{0.1}=283.24..
Quadruple Intensity;
L=\frac{ln(10^{12}\times 4)}{0.1}=290.173..
If you look at it, difference = constant of 10ln2
Percentage is slightly different between...