How do I prevent the options of a second user picker field taken from the same role from being the same?

[Katie Weiss]

I have a set of people under the Developer Role.  I have two User Picker custom fields - one that indicates the Developer and one that indicates the Peer Reviewer.  Both User Pickers pull from the same group of people - the Developer Role - because we have limited staff and developers are also the reviewers.  So, after the Developer has been selected, how do I remove the developer name from the peer reviewer user picker drop down thereby preventing the Peer from being the same person as the Developer (obviously a bad idea  )? 

[francis]

I would create a transition allowing to set the 'actors' and validate in the transition that both fields have been provided and that these are different.

[Katie Weiss]

Yes - that's what I've been attempting to do.  I was just hoping that there was an easier way - like if you could just populate the user picker with the "developer" role names minus the person that was selected for 'Developer'...