Q:

Question is marked as 'Duplicate', but the original has been removed

Today I was looking for the meaning of 'Roger' in radio conversation then I found this question. What's strange is that it is marked as a duplicate of What does “Roger” mean in war movies?, but this question has been removed! 
This subject has already been discussed in StackOverflow's Meta, but I'm not sure what should be done to the duplicate question (of no other, currently). Should it be also removed? Should it cease to be a duplicate (is that even possible)? Leave everything is it is now?

A:

At the time it was marked as a duplicate, it was a duplicate. The system has been amended to inhibit the deletion of such questions (that is, target questions can no longer be deleted).
The only way to remove the duplicate label is to re-open the question; but since it already has relevant and correct answers, and it would simply be closed again as general reference, there's no point.
In fact, the "removed" question is still there, although it's not shown to those without the Access to moderator tools privilege (that's 10,000 rep), so that label does serve some useful purpose.
There may an argument for deleting the question that's still there, although its presence did presumably stop you asking a similar one!

