See the multi-flow download widget, might be a good option!
Another solution might be using the executeMicroflowInBackground java action from the CommunityCommons module.
Add this Java action to your microflow twice (for creation and downloading of PDF 1 and for PDF 2). I haven't tested this for this particular case but this has worked for me in similar situations.
You could also create a zip.
https://appstore.home.mendix.com/link/app/1978/