Different Image DPI matter?

I am creating some of my books via the page  layout program, Scribus.

Does it matter that the images in the book are of different DPI, so long as they are at least 150DPI?  I have been inserting the images into the program and then if I need to enlarge them I click on the "keep proportions" and then increase resolution to make the images larger, but therefore making their DPI value smaller.  So some images are say 300DPI, whilst others may be bigger than their native resolution and be 238.44DPI

Does this matter?