I just watched the nineteenth episode of the first Season Stargate SG1.
Since the Series aired long ago, I will not bother thinking about Spoilers, so if you don't know the Episode and want to see it yourself, it is time to stop reading.
Anyway, the Episode is about SG1 on a "normal" Mission to a Planet (to be specific PX3-989) where the Altairans were settled on. Because of a catastrophic change in the climate, the Altairans couldn't live there anymore and transformed their bodies into Androids.
So far so good. SG1 was cloned and didn't know that from the first moment on, of course, the rebelled and went back to earth. Doc Fraiser didn't find a Heartbeat and was worried.
The story goes on and later the "original" SG1 (the human beings) are woken up and encounter their Android beings. After some resignment and dialogues, the Androids know they aren't the "original" and see that there is no possible way of returning and stay at the planet while the humans return to earth.
Now, I am getting close to the point, which I wanted to flesh out in this post.
What makes a human human and was makes a mind "unique"? If teleportation would exist and had a malfunction and somehow now two of you exist, who is the real one and how could one determine?