This is quite right and since the recent Caffeine and Panda updates, a lot of websites which previously had been filled with duplicate contents have experienced drops in the number of their indexed records online and their overall rankings on Google too suffered up to a degree. The best example to mention in this connection can be some article directories, lots of them have lost thousands of pages and their traffic shares too have decreased considerably, all because of duplicate content filter.
It is definitely a winning strategy always to write uniquely and preparing original copies plus contents for people to access and study, avoiding the shortcuts which after a while may turn out to be tragic. There is no use anymore, pasting copied materials from other blogs and directories on sites because Google no longer likes arriving on websites and finding materials it has already scanned the original somewhere else. Patient authors who write in a unique way will have better web ranks.