Does this code mean Greg is unplayable, or what does it mean?

Just curious. Will another Greg spawn if the original Greg becomes playable? I know or think that the two ghost couple that came with Windenburg and reside in that big old building with the maze thing respawn...I could be wrong though. And I also think that one of the famous Sims come back if you delete her, I think she's a teen? Just wondering if Greg might meet himself if one of my Sims manage to befriend him and marry him. Please educate me?