Thank you very much for the file and for using Dropbox.
There is not really a problem, but what you see is the “original MoSpline”.
Move the MoSpline away from the Cloner, and it will become clear. (To see the effect: Move the MoSpline away, or set the Cloner to Transform: Position [any value], or Object>Offset the Clones.)
You can set the MoSpline also to Object> Display Mode> Line, and the appearance of that problem is gone.
All the best