Did you find a solution? I have this problem as well both with print "booklet" and "multiple". Both options scale and add extra margins. I am using Acrobat DC 15.020.20042. I did not have this problem with the earlier licensed non-subscription versions of Acrobat.
Unfortunately, the Print Booklet feature in Acrobat was designed to fit the logical pages of the booklet into the printable region of the physical pages. That means that unless your printer supports edge-to-edge printing (most toner and inkjet desktop and enterprise printers don't support this), the pages are shrunk into that printable region.
For PostScript printers, the printable region is determined by entries in the PPD file. You could conceivably edit the PostScript printer's PPD file to force the imageable area to match the physical page sizes, although this is a fairly non-trivial task. For non-PostScript printers, the imageable area may in fact be hard coded into the printer driver.
- Dov