Pdf – Printing from PDF changes orientation

Foxit PDF editor (not the reader) can do it, you install it, open your PDF, choose document --> layout --> right click the page you want to crop and choose "clip content".

Supposedly the drawback to the free evaluation version is it adds some sort of watermark... but I can't see it. Maybe it got removed when I cropped the page. Or maybe page cropping is not a big enough change for the watermark to be added.

IF the excessive 'border' is on the left of one portrait copy and on the right of the other then reducing any gutter setting (Page Layout, Page Setup, Margins) may help - if it is not already 0! Otherwise Reduce Outside and Inside to suit.

If there is too much 'border' at the top and bottom reduce Left and Right Margin values.

With all settings at zero I doubt there is any way to reduce borders further (one at least is likely to be required by your printer).

However, you may be better off with Book fold rather than 2 pages per sheet. Gutter there controls the space between the two images (presumably you would want that set to about 0.4") Top and Bottom then rather more logically control the margins above and below the portrait copies and Outside the left and right borders, as a pair (Inside is like Gutter for Book fold).