funny "doublings" in PostScript output

[Kieren Richard MacMillan]

Hello, Mats (or anyone else who might know what's going on):

I've been playing around with the output from lilypond, putting it 
through ps2ps, and then editing it in Illustrator, and I've found 
something weird: many objects are doubled, apparently for no reason.

I noticed it first with slurs and ties, though because of the 
complexity of those graphics, I figured it was necessary. However, each 
clef element and accidental in the key signature is doubled! Noteheads 
and regular (i.e., note-attached) accidentals don't seem to be doubled, 
nor do articulations, barlines, or anything else I've run into so far.

Any thoughts on why this might be so? Is it a byproduct of the ps2ps 
process or something in the way lilypond generates the output?

Just curious,
Kieren.