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I have not a clue why Bitcoin Core put them there, I did not move them nor instruct to put them there.
Maybe somewhere is noted that this is my standard file location?
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If you didn't put them there, where did you download Bitcoin Core? Did someone else have access to the computer?
knightdk did a great job answering your questions and if you have downloaded the real version of Bitcoin Core, it behaves as he explained as to where it puts (or allows you to put) the wallet.dat.