Select excluded value from another list

[#1]

is there a setting that allows you to prevent the selection of excluded value?
In my application, I noticed this behavior - after selecting values ​​from one list can not be selected are excluded from the second list. I would like to determine if it depends on the application settings, the data model or maybe the application. Does anyone of you met with a similar case?

Darek

[#2 · Accepted solution]

I found the cause. The reason was simple. On one of the related fields I had a listbox with the "Always one selected" .... By the way, change the selection by choosing an excluded item was not possible even if the selector with the option "Always one selected" had selected value associated with new choice .