Why does it paste a different btc address than the one I copy ?

This might be a noobie question but it happens in two different desktop wallet now I realize it happens even in windows notepad : If I write the displayed address manually and delete the last letter, copy that and paste it still in the notepad, now its a whole different address again.Now if that's a security mechanism, it just doesn't work : I went along with the address that was copied to receive funds (luckily not much) and didn't receive cause this address isn't mine.So I tried with exodus wallet, manually copy the displayed address, but it wasn't valid so again I went along with an address that turn out to belong to someone else.Now on exodus I believe you owe two addresses : a segwit and a legacy one (correct me)So I took the second one (more conventional one that stars with a 1), manually copy it and it turned out to be valid and I received my money. But still I looked up the address that it copied and it stills belongs to someone else who used it 4 days ago.What kind of sorcery is this ?thanks. via /r/Bitcoin http://bit.ly/37NVQlP