How to handle duplicate attribute names and hexadecimal values

Question

I have an unformatted XML file like this:

    Hi
    
    <         


        

Answer 1

<ROOT>
  <A0>Hi</A0>
  <A1 A="hi" A="how" A="are" A="You?"></A1>
  <A2 A2="Bye"> </A2>
  <A3>In this tag have Hexa deimal value </A3>
</ROOT>

Duplicate attributes (on the same element) are not allowed in a well-formed XML document by definition.

Therefore the provided text isn't an XML document, cannot be parsed by any compliant XML parser -- and therefore, the described problem cannot exist.