Is this the MacPro5,1 SMBIOS ?
If so an easy solution is to change it to something else for the install, one person said they did that and switched back once the install completed.
Another option is to run the latest Clover Configurator and then copy the updated BIOS / firmware information to your config.plist.
Newer Clover versions should detect outdated firmware and pass updated info to the OS.
Someone mentioned the old softwareupdate --ignore trick and another mentioned the right click and ignore method in the App Store app.
I changed to iMac 14,2, installed and then changed back to 5,1.
The problem is that Mojave, just like High Sierra, wants to do a firmware update to the 5,1 SMBIOS.
Currently testing to make sure everything works. So far, everything except audio and I suspect that will work as soon as I rum MB and install it again.
EDIT:
OK, no MultiBeast yet, so - following toleda's instructions to remove all previous audio fixes:
go to Libraries/Extensions and delete AppleHDA.kext, Lilu.kext
Mount EFI, open config.plist and remove all 3 previous audio patched for High Sierra.
Download new AppleALC.kext and Lilu.kext, put in EFI/Clover/kexts/other
Reboot. Open preferences, select Digital audio and I have sound back.
