Because you didn't consider the + operator
In fact the output of first alert is "false", not "is return/cancel = false"
this happens because the == operator is comparing the string "is return/cancel = Return/Cancellation" with the string "Return/Cancellation" and of course they are not equal and the output is false.
If you change the code to
alert('is return/cancel = ' + (selectedVal == 'Return/Cancellation'));you will see the correct result