It's very common around here, particularly on old buildings, to have different aged roof coverings on different sections. Some folks replace individual slopes as needed - if there's a few more years left on one, but not the others. My last home had a standing seam metal roof over the original part, 2nd layer of fiberglass shingles over addition 1, one layer of old asphalt shingles over addition 2 and a new fiberglass shingled roof over addition 3. In an attic, there was one small area that had the original oak shingles. In your first pic, is that really a shake roof or are they shingles?