I'm probably just being a clueless newbie, but...

I'm probably just being a clueless newbie, but...

I keep getting repeated choices on my checkboxes and multi-selects. A choice will appear several times in a row when using the form, but only once while editing it, so I can't delete the duplicates. Even if I move the affected choice, the duplicates remain. They disappear if I delete the choice and re-enter it, but that's extremely irritating and time-consuming. There must be an easier way to deal with this. Is there?