by mistake several win32 agents got installed on win64 hosts
since upgrading from 32 to 64 is not possible using automated install, does leaving a 32bit agent on a 64bit machine prevent some functionality?
I think that you will not be able to manage anything 64bit on the system. For example, Windows keeps the 32-bit apps separate from the 64-bit, so you won't be able to install any 64-bit apps.
I would reccomend uninstalling the 32-bit agent and reinstalling the 64-bit agent. You may be able to use the Bulk Installer to do this.