I was checking out the outlets in my house, that's when I discovered 1 outlet didn't have an ground wire attached to it. I looked inside the plastic junction box, I could see 2 ground wires twisted together then looped around the screw at the back of the box. Does it mean the outlet is already grounded?

If it's not grounded, can I just attach a copper wire to the ground terminal on the outlet and twist it around the ground wires?

Also, the previous owner attached a cable on the opposite wall of this outlet, but it only has 2 wires: Hot and Neutral

I'm going to install an additional outlet there, I already purchased a metal outlet box. Since there is no ground wire, will the outlet be grounded if I just attach a copper wire to the ground terminal and loop it around the screw on the metal box?