Dual units for part & assembly documents, not dual dimensions

Is there any way to have either parts or assemblies or both to have dual units?  By this I mean including the mass?  We have a situation where our customers prefer their approval draiwings we submit in metric but we supply our shop drawings in Imperial.  We would like to have the two different drawing documents refer to the same models but not have to change the units to suit the drawings.  Any Ideas?

SolidworksAssemblies