If you export two reports to PDF and want to merge them into one, or combine them with other PDF files, you might want to look at a free tool I just discovered called PDFsam. This isn’t a trial version of something but a free open source tool. I tried it recently when I needed a way to merge a Word doc and a Spreadsheet into a single PDF, rotating the Spreadsheet 90 degrees in the process.
Whenever available, I usually opt for “free open source software” (FOSS). Software that is open source means that it was developed by a volunteer team that provides the source code for their application for free. Not only do you know it is free but it makes it much less likely that someone will try to include malicious code. If you want to see what is available in FOSS you should check out SourceForge.net, one of the most reliable sources for FOSS.