When I merge two filled-out forms with pdfunite (latest git, poppler-0.62.0-59-g62f2b0bb), the result renders correctly in evince, but not in other viewers such as Adobe Acrobat Reader on iOS. I also couldn't get it to print correctly. I'm attaching a filled-out form, the result of "pdfunite N.pdf N.pdf N2.pdf", and screenshots of how the result is rendered in Adobe Acrobat Reader. This may be related to bug 99141, which made pdfunite work for filled-out forms in the first place.
Created attachment 136991 [details] A filled-out form
Created attachment 136992 [details] Result of "pdfunite N.pdf N.pdf N2.pdf"
Created attachment 136993 [details] Page 1 renders correctly
Created attachment 136994 [details] Page 2 doesn't render correctly
Usually, all but the first page doesn't render correctly, but I also had a case where even the first page was corrupted. In evince, the document looks correct, and I can create a printable document in evince by printing to a file. (In that process, the form fields get converted to static text, of course.)
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