We used to have all sorts of problems with misfiled slides. Most of them
were slides being filed in with the wrong year. I'm not sure if this is what
you are experiencing. To rectify this I started using different slide colors
for each year. We haven't had to duplicate any slide colors yet...but it
sure has cut down on filing mistakes. It grabs your attention when you are
trying to put a green slide in a pink slide year.