How to update a trackback?

If I send a trackback to someone else’s blog (that is, I am tracking back to them, using the “Send trackbacks to:” field on my post Edit page), then I change my original post, do I need to re-send the trackback so their page gets the update? I’m not seeing the update happen automatically, but don’t want to send it twice if that’s going to make it show up on their page twice.

Thanks,