32 & 64 Bit in one (Windows)?

I’ve successfully compiled a 64 Bit VST on Windows now.
Does one absoutely need to create 2 DLL’s on Windows for the same plugin if one wants 32Bit and 64Bit versions (unlike on Mac) ? Would it theoretically be possible to put everything into 1 DLL ?

Also, I suppose the 2 DLL’s will use the same 4-char codes as VST identifiers?

There is no equivalent of the macos fat binaries on windows, so you have to build two DLLs. Using the same VST id for both dlls , and keeping them in the same folder, is ok.