Modern office products has a feature to track and highlight changes. Old versions of Miscrosoft Word used two colors (striked-out red for deleted and green for inserted text), while recent version changed highlighting style to one color (striked-out red for deleted and underlined red for inserted). As I can see Open Office uses only one color too. What might was the reason for this change of style to highlight difference?
I'm developing a web application with similar functionality. Using one color seems OK when there is small amount of changes, but it become ugly when there is a lot of changes. Highlighting with two color looks fine in both cases.