Overprint, also called overprinting is the process of printing one image on top of another.
Normally only the top layer will be seen on monitor, the layer underneath remains hidden, and this can easily lead to unexpected and undesired printing output.
Therefore, it is important to uncheck overprint function when saving data.
It is also possible to set the surface (fill) and the line (stroke) separately, so please check carefully.

Tip. When duplicate printing effect is required, it is possible to produce overlapping effects by modifying image transparency.
And printing errors can be prevented by checking and ensuring correct printing data is saved.