Hilary,
Thanks for your response. Here's what I'm trying to accomplish.
I have a repeating table inside of a repeating section. In the repeating section is a drop-down list box that picks the category of gear. The CopyTable command is bound to this drop-down list box. The repeating table is filtered to only show items that the CategorySelector = GearCategoryFromTable. This is all working great.
I added a rule on the drop-down list box that if it is not blank, to disable it. That way, they cannot pick that category again, causing duplicates. This is a cheesy workaround for now.
Another problem, when they add another section, they can pick the same category again, appending the table with duplicates. If I could find a way to make the same selection in the drop-down list box not available in the next section, that would be nice.
But if I could find a way to filter duplicates, that would be the best solution. Could expand on your line of thinking a little?