The Mozilla Ideas Exchange is great and an excellent way to get contributions and engaged the community but looking through the many ideas I noticed that many ideas repeated (despite the suggestion in the guidelines to search first) and I thought it would be possible to somehow suggest a link or group these ideas together, but I haven't seen the option for this.
The advantage I see for this linking or grouping feature is the follow:
1) Eliminate duplicates as community will help highlight duplicates by linking them
2) Potential to add a combined Kudos score (but still eliminate duplicate votes by users across each one).
3) Informs those who have submitted duplicates that their idea has been linked to another one that already existed