Printing two different invoice forms at the same time

Hi All,   I have a client that prints two different invoice forms (they are quite different from each other in layout & info)   They would like to be able to print them both at the same time.  I am unable to do this with a sub report (I think it has to do with the way the work files are created).   These would need to work from history as well so I can't use the invoice entry file as a source.  

Any ideas would be appreciated!

Bob Osborn
ACI Consulting