avoid automatic (?) rotation when combining multiple files into 1 pdf

As I do often have to mark up (stamp) and print large number of single A3 size pdfs (converted dwg files) I am combining them (explorer) into 1 new pdf. Thus enabling just 1 print job instead of 50-100 !

So far no problem - combining works fine & all drawings are even landscape.

However when applying custom stamp on each sheet (first time all the way in acrobat - all next sheets with copy - paste because:

• much faster
• often resizing required
• sometimes even rotating required.

Seems originally not "landscape" orientated files were (at least in the view) re-orientated causing the applied stamp to be 90 - 180 or -90 degrees offset

When I manually remove the stamp on this page and insert a new one via Acobe Acrobat (not copy paste) the orientation is ok. Rather amazing.

Got some more related questions but think 1 step at the time is more convenient.

As often 50-100 dwg's are involved the copy-paste method (after resizing once) turns out most efficient till now.

How can I control / avoid the automatic rotation or anticipate on the (obviously) rotating stamps ?

I will have to move the stamps anyway because I can hardly ever put a stamp at the same position on a drawing.

[It turns out to be almost impossible to get draughtsman to leave an empty space on each drawing ...]

Once again thanks in advance for any suggestion !