For example: I have a blog page on "XYZ.com/abc", it is also published on "ABC.com/abc" and "PQR.com/abc" as well.
So it is duplicated from "Xyz.com/abc". Added Canonical tag in all above 3 sites pointing to "Xyz.com/abc".
Is adding canonical tag in same website okay?
Need to add in duplicate page only?
What will happen if 3 websites got indexed?
Looking for expert opinions.