I am assuming your version of Server 2008 R2 is x64.
If you wish to install and make available x86 drivers for each of your printers you need to make sure that the driver.dll name associated with your printer is the EXACT SAME. The drivers provided by your manufacturer will OFTEN be named differently than the ones provided by Windows. It is for this reason that installing manufacturer x86 drivers with Windows x64 drivers will not work and will often say "x64 driver doesnt exist" or some BS like that. Even though they are installed "properly", the printer will not be able to make the connection between the different file names associated with the x64 and x86 drivers.
My suggestion is to download both the x86 and x64 bit drivers from the manufacturer, uninstall the printer entirely from Server 2008 R2, and then reinstall everything using the Manufacturer drivers.
Once this is done, you can right click on the installed printer, select the "Sharing" tab, and click the "Additional Drivers" button and check off the x64 and x86 drivers as Januismer suggested.