Please explain what you mean by "collate two separate reports".
On a copier with the collate feature you typically end up with all of Report1 in one group of pages and all of Report2 in another group of pages. Much as you would if you printed Report1 and then followed by Report2 on a printer.
If that is what you want, then merely allow the user to input the number of copies desired prior to going to your REPORT FORM command(s) and then Loop through the number of copies desired.
You would print a single copy the first report in its entirety followed by the next report and then loop back to begin again - resulting in multiple collated copies.
If, however you did not want 'collated' reports, but instead multiple copies of each separate page, then the best way might be to control the Print Copies parameter of the printer.
Good Luck,
JRB-Bldr