990423 - how to distinguish between 32-bit and 64-bit installers?

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VS2010

msi

64-bit

Hi We know that 32-bit exe files can't run 64-bit dll's (call their functions) and vice versa. We know that a 32-bit package (MSI Windows Installer) may be installed on a 32-bit Windows and a 64-bit Windows, while a 64-bit MSI package may be installed only on a 64-bit platform.
Now, I've a VDPROJ project to make 32-bit and 64-bit Windows installers. Also we know that MSI can't package both 32-bit and 64-bit installers at the same time. You may have a 32-bit MSI or 64-bit MSI, each of which may install 32-bit program which uses 32-bit DLL's or 64-bit program which uses 64-bit DLL's.
Am I rihgt until now?
Now, I distinguish between these MSI building by the combobox in Configuration Manager section. There're two configs, one is x86 and the other one is x64.
My program needs ffmpeg dll's which are released as 32-bit and 64-bit. In the vdproj, I've specified them to be installed, but each time I need to build a 64-bit MSI, I should replace them, before building the package.
Now I see that there's a "Condition" property in the list of File Installation Properties section which may install or not to install the file based on a condition. I know that I may specify VersionNT64 or Not VersionNT64 as the condition, but this can't help, because I don't mean the platform which the package is installed on. Please remind that in a 64-bit platform both 32-bit and 64-bit packages may be installed. But I need to know what is selected from the combobox, x86 or x64, and based on this, I decide what dll's to install.
Is there a way to refer to the selected configuration manager in the condition property of the file installation properties list?

What I have tried:

I looked for the predefined variables which I may be use in the Condition property and also its format. But I couldn't find anything.