For Asus, Dual mean card has 2 fans (Strix - 3 fans, although to add confusion, some lower end cards are named strix despite having only 2 fans, but then again such cards do not create enough heat to justify 3 fans); OC - card been factory overclocked
So, 1060 Dual OC means two fan, factory overclocked gtx 1060; and 1050 ti strix OC means two fan, factory overclocked 1050 ti.
Which is better? 1060. But 3 gb version is probably least future-proof card in the market now. I would suggest looking for rx 570 instead.