How did you generate the bottom image?
The top one looks like economy mode on the printer to me…
On the top image I include the two pictures in a more big picture, and I print this.
On the bottom image, I print separately the two pictures.
The printer has the same settings.
what happens if you use plugin functions to load image?
e.g. use JPEGImporterMBS for a jpeg image.
Draw into new picture, use JPEGExporterMBS to write it back to disk.
Pass ICC Profile from importer to exporter.
As the plugin does not convert color spaces, it may come out correct.
I fear that the conversion of color spaces when loading image via GDI+ may break them.