Re: one more issue on removing dup records

some releases do not need to have ";headlines;" to be added in the
"display_on" attribute.

My solution relied on the fact, that "release" elements in Data Group
A had "display_on" attribute with value "headlines;". Any other value
of "display_on" attribute would mean, the element is in Data Group B.

Now you are saying, some "display_on" attributes may not have value
"headlines;".
Will such elements have "display_on" attribute with value "" (empty
string), or is there any chance that some "release" elements may have
"display_on" attribute missing all-together?

You can try by adding a "or" condition in predicate(s) to accommodate
additional rules.

--
Regards,
Mukul Gandhi