Hi lenka,
as far as I know there isn´t a way to do this. The only thing I know is that in the book "Designing Forms for Microsoft Office Infopath and Forms Services 2007" (Scott Roberts, Hagen Green) in chapter 20 there is an example for building an Infopath-Add-In with features to copy data between two forms - but I don´t know if this sample runs with Infopath 2003.
Regards,