I'm using Version 7 and an advanced licence.
I find myself having the same issue as here : https://www.phpdocx.com/en/forum/default/topic/927
An horizontal line appear at the bottom of the page if it's a merged PDF. Not in a merged DOCX however.
In MultiMerge.inc, I already had $pdf->setPrintHeader(false); as explained in the post above but still the issue is here.
So in /phpdocx/Classes/Phpdocx/Utilities/MultiMerge.inc I added the following :
It seems to work but do you have a better solution ?