The SetaPDF-Merger API is able to concatenate PDF documents with dynamic content like PDF forms (AcroForms) or any other annotation.
To avoid naming problems all named objects or form field names were renamed. They were simply suffixed with an underscore (for form fields) or a dot (for named objects) and a number (the number of the current processed document).
The API also takes care of internal links.
Internal links will only be written if the document is imported as an entire document with all pages (the $pages-parameter of SetaPDF_Merger::addFile() has to be set to false)
As already stated form field names will be suffixed with an underscore and a number.
The API is not able to merge pages with form elements from one document a few times! Currently the API didn't recognice that issue, so it's your turn to avoid this!