There is a couple of options you could try:
1. Using Columns
In your report go to File > Page Setup > Page (Set Paper Size and
Orientation to A3 Landscape) then Go to the Columns tab and set:
Columns to qty 2, Widths as per the width of an A4.
This should report back all data but not the
headers/footers..............I think.
2. Use Sub Reports
Create a "Master" report >
In your master report go to File > Page Setup > Page (Set Paper Size
and Orientation to A3 Landscape):
Insert the 2 reports you want to view side by side as sub reports.
These are a couple of basic techniques and may require some "tinkering"
on formatting, etc.
Both of these has worked for me in past.
Tim