Hello,
I noticed a behaviour I don't understand with some PDFs. They are hybrid-reference file where both cross-reference sections carry the same informations (there are 9 meaningful objects and the 9 are referenced by both sections).
When I sign the document twice, the second signature invalidates the first one. This seems to be due to the copy in the update trailers of the reference to the original cross-refernce stream, i.e. :
trailer
<</XRefStm 78305/ [...]>>
Is this a bad practice?