we have a mixture of floating licenses so do we need to install them on separate license servers?

We have a mixture of floating licenses some platform with web module licenses and some platform with web and desktop licenses.  I want to be sure the ones that have desktop are available for the people who need those licenses.  Do we need to install on separate servers for this to happen?  I'm concerned it is first come first serve and someone with web enabled will tie up one of the licenses that has desktop.  Will the simple act of only having the add-in selected with desktop and web make sure that they are the only ones to get to pick up those floating licenses?  Or is it if we have more than our allotted platform/web log in they will grab one of the licenses with desktop even though they don't have it enabled?