WGM/MCX woes

All, I am having some trouble with WGM and hoping someone can help me out here. Situation: 150 macs managed through WGM on a computer list called "Normal" All MCX setting are on. We also have user called "exam" in WGM which also has a different set of MCX settings. The "exam" user account will be disabled until exam day. What we are having trouble is with the computer list "Normal". Since the "exam" user is logging into a computer which also happens to be on "Normal" computer list it grabs those MCX settings as well. The thorn is mostly with the Dock preference. Since my "normal" cpu list has 10 items and "exam" user has 3 items, It gives me the all 13 items. 1. Mass moving computers off and on my "normal" computer list. I could go into the Inspector section of the computer list and remove the computer attribute and adding it back in. Anyone done this before? I was playing with this earlier and noticed some of my clients appeared twice (same mac address) in the all_computers list with the "_1" in all the duplicates computer names. 2. Presets. I'm not too savvy with Presets so I don't know if this is another options for me. 3. I could disable the Dock MCX on my normal list. and reenabled it after exams but i would need to recreate the whole dock again. (takes a while to do). I've tried option 3 and takes too long. I'm going to play around with option 1 and modified the computer attribute and see what happens. Thanks. Jason