Hi Mohamed,
We can add
multiple digital signatures in a PDF document by appending additional
signatures to an already signed PDF file. We have checked the provided
screenshot on our end, the document contains the trail watermark in it. When we
add the signature for the first time without a license key, the trial watermark
will be added and the document to be modified. So that, the second signature is
Invalid. This is not an issue. To overcome this, we have to apply the registration
license key to avoid a trial watermark and get a valid signature.
Please refer to the below documentation for more information,
UG: https://help.syncfusion.com/file-formats/pdf/working-with-digitalsignature
Blogs: https://www.syncfusion.com/blogs/post/create-validate-pdf-digital-signatures-csharp.aspx#add-multiple-digital-signatures-in-a-single-PDF-document
KB: https://www.syncfusion.com/kb/9801/how-to-apply-one-or-more-digital-signatures-to-a-pdf-using-c-and-vb-net
Please let us know if you need any further assistance with
this.
Regards,
Gowthamraj K
