The info by Olli is slightly incorrect. SD2 is not copyable because most (but not all) CD writers correct (or change) the data (like Plextor 8432T).
With these CD writers, if you make a copy and re-make an image from the copy, then using the excellent Daemon CD emu the image does not work.
The problem indeed does lie with the CD writer. Come on, Plextor we need a new firmware update to fix this.