Combining torrents that contains same files

[bcdgh]

Hi;

So far, I have seen many torrents that the exactly same files are shared.  Sometimes all of shares dont have have %100 of file/s. In such cases, so far, several times First I downloaded some parts of file from one torrent and then I moved and renamed these files to download directory of other torrent and I could achieve downloading %100 of file/s.

So, Why doesnt Bittorrent detect files that are shared via different torrents and join all the peers together?  

If this feature isn't implemented because of some reasons; then
What about a feature that combines 2 segmented files that are partially downloaded from different sources ? This feature would be amazing especially for video files. Once, I spent my hours for combining 2 segmented video files manually on a video editor.