It seems to me, the first and second geckoes differ not only details of coloration but also proportions of a head and a degree of ribbing of scales. But the second photo insufficiently close to judge with confidence. Of course, proportions may be determined by sex (the first gecko is a male and the second is a female - isn't it?), and scale's ribbing also can be different at different populations depending on humidity and density of a substratum.
The fourth gecko look exactly other sp than first two but from the same clade of genus (related to H.isolepis). All of them are ground-dwellers so have smaller size of scale and ear opening, elongated body etc.
I definitely saw recently a photo of similar Hemidactylus in one of papers I have. But as usually I have forgotten in what paper and under what name.

. I will try to find it.
The third gecko may be H. robustus (closely related with H.turcicus) or other sp. from so called "Arid clade" of genus. There are at least 12 members of this clade known from Somalia (H.bavazzanoi, H.citernii, H.puccionii, H.arnoldi, H.barodanus,H.granchii, H.jubensis, H.macropholis, H.robustus, H.sinaitus, H.taylori, H.yerburii pauciporosus) and it is clear that the African Horn is the centre of origin of this clade. So each exemplar founded in Somalia with exact label may be important for scientific investigation of this group.