Alice-chan's Manga

Good story but I’m confused about something. Since the character Dan-I was originally a part of this webcomic world (she and the purple hair girl has always been friends even before real world Dan-I came to the webcomic world), does that mean that the Dan-I from the real world took over the body of Dan-I in the webcomic world??? If so, when Dan-I of the real world goes back to the real world, shouldn’t Dan-I still be a part of the webcomic since the webcomic Dan-I has always been there in the first place??? I don’t get why Dan-I’s existence is completely forgotten and wiped out of the webcomic world when she was a part of the story even before the real world Dan-I came into this fictional world? Shouldn’t the previous Dan-I of the webcomic world (the one that grew up with the purple hair girl) take back its original role when the real world Dan-I goes back to the real world???
I hope that wasn’t too confusing, I’m not great at explaining or names but I tried. Maybe I’m thinking too much but I’m just confuzzled... lol