Selection in one dynamic panel clears out selection of another dynamic panel

I have a series of custom dropdowns made with dynamic panels and repeater tables. The behaviour I am trying to create is that all the dropdowns have the same content, but no duplicates will be permitted. So if a data point is already present in one dropdown and the user selects that same data point in another dropdown then the first dropdown loses its selection. I am struggling at how to go about this, I can’t seem to wrap my head around this. Any suggestions on how best to construct these dropdowns and create the interactions would be appreciated.

upload your .rp file please.