A normal curve with μ = 20 and σ = 3, and a normal curve with μ = 20 and σ
= 6.

first of all, you can't just cut and paste. If you mean a normal distribution curve with \mu=20, \sigma^2 =3 and \mu=20, \sigma^2 =6 , it's just two normal curves both centered on 20 with the crest of the curves at \frac{1}{\sqrt{6 \pi}} and \frac{1}{\sqrt{12 \pi}} respectively. Keep in mind that the second curve will be shorter and "fatter". More specifically, the graph of any normal curve is just the graph of the function

f(x)=\frac{1}{\sqrt{2 \pi \sigma^2}} \cdot e^{-\frac{(x-\mu)^2}{2\sigma^2}}

I hope this helps.