"signed" in the name document when you save

Hello,

if you insert a image sign in a document pdf with the Adobe Reader XI, when you save the document, the program insert the Text "-signed" at the end of the name. For exemple, in the name "doc.pdf", it will be "doc-signed.pdf". Please, I want not include this text, I want to have the same original name, "doc.pdf".

I have searched in Preferences and I not find the option to not include the "-signed" in the saved name when you sign a document.

Thanks,