Yes it does. Windows doesn't support running 32-bit drivers on a 64-bit OS (or vice-versa). Windows doesn't (in general) support loading 32-bit DLLs into 64-bit processes (or vice-versa). To do this, you can provide both 32-bit and 64-bit DLLs (as various shell extensions, e.g., do), or you can provide 32-bit or 64-bit thunking DLLs. Or you can provide your stuff as COM components (which, simplifying the technical details, provide transparent thunking in a lot of scenarios).

Presumably, the VPN software is either largely implemented in a kernel module (which would need to be 64-bit), or it's a Winsock layered service provider (which is, IIRC, a user-mode DLL), and therefore needs to be available in 32- and 64-bit versions.