I don't know shit about this stuff, so take what I'm saying with a grain of salt.
But from what I can see it's not necessarily about overkill, rather than pointlessness. The possibility of something going wrong with just the single cordelette was more likely to be the tree getting pulled out than the cordelette undoing, or snapping, or whatever. So wouldn't it make more sense to find another anchor point as a back up, rather than backing up on the same tree? It just seems like a waste of time to do what you'e done.
But like I said, I know next to nothing on these matters...