Trails Effect-Video plays twice at the same time

Hi,
when I apply the standard Trails effect in my project, it seems that at a certain point FCP starts to play the video I'm editing twice at the same time, but from different points in time of the actual video. It seems to have something to do with the Echoes parameter, but I'm wondering if there is some way to control this by-effect (so to say). So that I could decide when the video starts playing twice, from what point on, and if I can turn this off entirely.

Thank you very much