No, a scapegrace is not someone who dates a scapegoat. I stumbled across this word when reading some blogs about words. The definition of scapegrace is a reckless or unprincipled person. They are usually wild and reckless.
The word comes from the word scape, which is a various of escape, and grace. The literal interpretation of scapegrace is one who has escaped the grace of God. We think of them as a scoundrel or rascal or reprobate.