First, make sure there is only one License Admin, and, most importantly, only one license folder for the entire site. In other words, when adding a new user, you install the client portion of Pro on the new machine, but NOT the server portion (License Admin).
If there is more than one license folder, you WILL continue to have conflicts. Remove any extra license folders.
Second, Users should not be added manually using License Admin. If you added any users in the users tab of License Admin, remove them. Then go to each user's machine, browse over the network to the server machine's ICETCP5_User folder, and browse down to the 4.4 folder and run the ConfigWizard program (ConfigWiz44.exe ?) found there. This program will assign a unique sequence number to that user. Do this for any users that are getting conflicts.
You don't have to reboot the computer after making changes in License Admin; but DO NOT ADD users manually in License Admin. This must be done by ConfigWiz as described above.