I believe that the yellow one is a female red-veined dropwing Trithemis arteriosa (I think, but not at all sure so don't quote me, that T. arteriosa is the only one with a wholly black tail-tip, at least in southern Africa). If you haven't already, I found that the "Africa dragonfly" website was the best place to look for images to compare.
On the red one, the tail seems to be thicker than Trithemis further south, and T. kirbyi, so far as I'm aware, has a wholly black pterostigma (pigmented cell on the leading edge of the wing). It looks more like Crocothemis to me, possibly C. erythraea with the yellow pterostigma, but I think that there are a number of red Crocothemis.
(EDIT - the nearly black base of the wing is wrong for C. erythraea, more like Urothemisassignata)