In some cases the 1099 form is not printing two forms per page on Mac OS.
We have found that certain printers respond differently and may need a either the form layout/margin changed or the Print Setup.
Using the default form, we found that the following margins were effective:
NOTE: To access the screen below, select File -> Company Setup -> A/P Forms.
If the margins are set as shown in the screen above, try scaling the printed page to 90-99%. We found that scaling to 99% instantly made the form print on 2 pages while 100% did not.
Scaling can be done in the Page Setup window as shown in the following screen:
Printers can vary so it is possible that different scaling settings will work better with different printers. Once you have the form lined up and it is printing 2 per page, you can then make the minor layout adjustments to the field placements by selecting File -> Company Setup -> A/P Forms.