Overlapping BMP source pictures separated

Environment:

Windows XP Pro, SP3
WordPerfect 9.0.0.896
PDFCreator 0.9.9

When I print to PDFCreator and the source document contains two BMP pictures one of which overlaps the other to make a complete image, PDFCreator separates the two pictures, thus destroying the PDF image. Can the separation be stopped?

Thanks in advance,
Adrian