I do that also. It is the intent of Corel to create a vector file with color fills to recreate the bitmap, but in vector. In order to fill an area with color it must be a closed object. So a red circle with a white circle inside it will have a red donut and a white circle, both with outlines. Same as an EPS file.

It takes a program specifically written for engraving to make a file that does not have those extra objects.

Philadelphia, PA (Really Bensalem)

When you finally understand it completely... it changes.

Its cos you are not limiting the colours , change the no of colours to suit the logo , like if its a red and blue logo , change the colours to rgb or cmyk and limit the no of colours to 2 or 3 (white areas count as a colour) , same can be done with black and white.
If you dont it will see pixelated outlines of the bitmap as a slightly different colour to the object and you will have a trace of the object and the "fuzzy" outline.