When importing a half completed torrent, and you continue downloading,
it looks like the ratio in GUI is based on the "downloaded" (completed) colum.

Now the ratio on the tracker and the ratio in GUI have a different measurement and can differ a lot when you import i.e. a 99% completed big sized torrent. I guess the ratio in GUI should exclude the "real imported" part here.

EDIT
I just realized this is in a situation where the torrent was a re-seed. So above is not an issue, and more important, i should think next time.