Many line breaks unexpectedly added when copying texts in PDF

[ReporterX]

I experience this problem in many PDFs.
But I don't get this problem if I copy the texts in another PDF reader.

Just try to copy a large block of texts.
For example, http://www.adobe.com/enterprise/accessibility/pdfs/acro6_pg_ue.pdf
Copy the paragraph "Adobe PDF and accessibility"

This is what I got:

Adobe PDF and accessibility
PDF is a standard on the World Wide Web and is also used to distribute electronic documents over corporate
networks, by e-mail, and on digital media. Users of Ad
obe Acrobat software can turn virtually any electronic
document or scanned image into a PDF fi
le. These files can then be read by anyone using free Adobe® Reader® 6.0
software. Many corporations, educational institutions, an
d government agencies use PDF to distribute documents
to the public or to groups in their organizations. PDF is
also the basis for new proce
sses; its support for accessible
electronic forms, digital signatures, password security,
and electronic mark-ups make PDF the ideal platform for
converting yesterday’s paper-based business processes to interactive digital processes.
Adobe is committed to providing solutions that improve the accessibility of both Adobe Acrobat software and the
information contained in Adobe PDF files. In
1997, Adobe introduced the Access.Adobe website
(http://access.adobe.com). In 2001, Adobe enhanced the PDF
specification to allow the creation of “tagged” PDF
files in Adobe Acrobat software. Tagging a PDF file make
s significant improvements to the accessibility of the
document, providing a mechanism to indicate the precise
reading order and improve navigation, particularly for
longer, more complex documents. It is possible to add altern
ate text descriptions (alt text) to graphics appearing in
tagged PDF documents. Tagging PDF files enables content reflow for large type display without content disappearing
from the edges of documents. Tagging also allows PDF file
s to be presented on smaller devices, such as personal
digital assistants (PDAs) and cellular phones.

[timvandermeij]

We already have a lot of similar issues open for this. Closing as duplicate of them, for example #2569.