Then I recommend splitting up your sources into 2 separate ones: one for your TVE sources, and another for the others. That way when you apply the XMLTV, it will only do so for the content that does not have native Gracenote mappings.
By trying to simplify your complicated setup (using a single import from one DVR to feed another), you have introduced additional complications (incomplete data because of XMLTV deficiencies). Split your sources up, and you'll probably find that it works better.
(EDIT: grammar)