Clone tool question

[ksht]

I am wondering whether somebody knows how can I get rid of artificial rectangle-like lines of the simple line cloned by clone tool? I use to draw a kind of complicated lines in different colours in PS. In order to copy the shape and the colour of the line I use Clone tool. It works excellently, but when time comes and I need to print the picture, ugly small straight lines appear near my cloned lines (interestingly, only in print). How can I get rid of this?
Thanks in advance,
ksht