Multiple logons by MS Win 2k Pro WkSta

I have an NT 4.0, SP6, server on a small 10 user network. My problem is being caused by the new Windows 2000 Professional Work Stations.

We only have a 10 user license and the new 2k machines are shown as having from three to eight logons in theServer Manager. This prevents us from having all of the work stations logged on. The 10 user license is already full because the two new computers have 11 logons listed.

If I disconnect any of the duplicate logons the whole work station is disconnected.

Anyone with any guidance in how to correct this will be greatly appreciated.