Will Playstation 4 data be overwritten?

I borrowed a Playstation 4 from my friend, but he now wants it back. I got one for it from my brother-in-law. Now I have pulled the data from the first Playstation 4 down to an external hard drive, and now I want to transfer it to the second Playstation 4. If I do this, will the data be transferred to the second Playstation 4 that is on it? If so, does it make sense to drag the data that is on the second Playstation 4 to the hard drive and then to pack my data onto the Playstation 4? Sorry if it sounds a bit confused.

Upload all your saved games via PS + and download them to the new PS4 (to your account). It is easier than copying everything, you have to download games again but everything you have earned in these games remains.