We use per device CALs on our Windows 2012 License server. We have 150 device CALs installed. We have about 45 thin clients logging into Windows 2012 server to get to their point of sale software. Our problem here is not the thin clients taking multiple licenses but it's the administrator's computers taking multiple licenses. I use RDC Manager to attach to the terminal servers on Windows 8. Other Admins here don't use RDC Manager, just the RDP app. They are using Windows 7. We are all getting multiple RDP CALs assigned to them.
My computer has over 30 permanent CALs assigned to it. There are days when my computer will take up 7 or 8 licenses. I have over 100 temporary licenses assigned to my computer!!
If a user calls and their terminal is getting a license error, I can go in and revoke one of the licenses for my computer, they get logged in fine. Do a refresh of the RD License Manager and I can see the terminal that user was having license problems on has a license from a week ago and the only new license handed out at that time is issued BACK to my computer!!!
If I install more licenses, our computers start eating them up. We had MS look into this about 2 months ago and they rebuilt the server and now we are back where we were at 2 months ago. Tried to re-contact MS on this but I have been waiting for 2 weeks for them to call back.