Why does the compiler cast automatically without going further in the inheritance=?iso-8859-1?Q?=3F_=96_stackoverflow.com?=

Why does the compiler cast automatically without going further in the
inheritance? – stackoverflow.com

While I try to run following code snippet, it's executing wrong overload
method. I'm confused why it does that? [testB.TestMethod(testValue) method
execute the public double TestMethod(double ...