I have PageStream 5 for MorphOS. The directory 

PageStream/SoftLogik/Printers/PPD

contains all the PPDs by vendor. It also contains the directory PPD with an exact copy of the parent directory, so all the PPDs are double in the archive. This takes 13 MB in size of the .lha archive and also disk space.
1) I assume it is safe to remove the second PPD subdirectory, right?
2) Can you then remove it from next build on?

Hi Markus, it seems the 2nd PPD directory has been left in the archive unnecessarily, and is a duplicate nested directory of the parent directory. If the 12.8MB of space it consumes can be better used with some other data then I would consider that the duplicate directory can be deleted or moved for backup purposes to another location, but if you have the PageStream v5.1.2 MorphOS archive already stored safely then there is no point in keeping that duplicate directory anywhere on your system.

Probably the other directories that hold drivers for other makes and models than the one, or more, that you own are likely to be of little use as well, so any drivers you don't use are probably wasting/taking up data space that could be better used, but that comparatively small amount of space (by modern standards) is seemingly insignificant.

You will have to wait for a response from Deron to know more about your second (#2) comment.