The two larger neutrals look as though they were installed after the smaller ones.
On both bars the unused terminals are in their factory positions, except for the bottom terminal on the left. It has been backed out as though the electrician planned to use it, but then didn't for some reason.
I suspect that the larger neutral which is doubled up with the small one was trimmed off too short to reach any of the higher terminals, and that there is something wrong with the bottom left terminal, stripped perhaps. Those aluminum neutral bars aren't the greatest.
The electrician should have tied it to the bar on the right, but that would have been a little awkward given that the other neutrals were already installed on the left bar.
Regards,
Brian
