I can view both .MPO and .JPS pictures in Corel PaintShop Pro X3, in 2D though. They are just JPG files.
It would be better if you change setting and save 3D pictures in .JPS format.
When you save pictures in .MPO format and then view in 2D image editor it is a single picture, but it is blurry. You cannot re-use it as 2D picture.
When you save pictures in .JPS format and then view in 2D image editor it is double picture, side by side horizontally. This way you can cut out half of the picture and use it as 2D image.