After getting your label:

Hover over the label 

and select the printer icon

Under  “Pages per sheet” select “2”

If your screen displays “Multiple” select that and then select “2”

You may also need to select the "Size" as "Printable Area". In some cases this can also be 160%.

The key is to locate the settings for “Page Sizing” and/or “Page Handling”

The postage you generated is a standard PDF file, so each printer can be adjusted to get the best and most readable print out available.