When Joke Theft is not Joke Theft?

I was named after my dad, about twenty-five years after my dad...

The above joke, is one I have used at many of my sporadic stand-up gigs. So you can imagine my surprise when reading an article about Comedy Opinions, the above Joke is attributed to another more famous comedian than myself a man named John-Luke Roberts... (See Here)

Now I have never heard of this guy or seen his act and I'm pretty sure he has never seen mine, so this is simply a case of two people having the same idea for a joke.

But now I have to drop it from my act... Which isn't too bad as I want to concentrate on Comic Poetry/Songs and General Comic Writing rather than stand-up, so it is to be forgotten and never thought of again...

This is a routine of mine that I believe doesn't include this joke...