It happened during migration from version 5.2 to 9.1.1.
Only one of the pages survived with PageTitle during the migration.

I have solved the problem by adding the below shown tags to the *.xml files.

    <ContainedComponent>
      <Name>PageTitle</Name>
      <Type>Literal</Type>
      <PassthroughAttributes>
        <Attribute>
          <Name>Text</Name>
          <Value>Page Title</Value>
        </Attribute>
      </PassthroughAttributes>
    </ContainedComponent>