Learn English – A word for one thing that is masquerading as two (The “Double Issue” issue)

I am trying to figure out the best way to describe this seemingly specific name, the "Double Issue". In English, Double has many meanings, but the main uses all basically mean 2 of something, in some way shape or form. In the situation I am about to describe, the word Double does not mean what most English speakers intuitively think it does. (Note I am not trying to dispute its defined meaning or anything)

If I were to call an issue release of some kind of content a Double Issue, most people will intuitively think it has twice the content, because that is what double means in most circumstances. However, for Weekly Shonen Jump (basically a collection of chapters of Japanese Comics released almost every week, usually of the Genre called Shonen), as well as many other Magazines it seems, It has a whole other meaning. In these cases, it is a single issue, with no more content than normal, that is labeled as 2 different issues. So, one week they will release issue 3, then the next, it is issue 4-5. they then do not release another issue the next week, and resume with issue 6 the week after that. Issue 4-5 is called a Double Issue by most English people, but to anyone who does not explicitly know what that means, they of course think there will be twice the content. Shonen Jump specifically releases only 48 issues. Over the course of 52 weeks, they release 48 Issues, with 48 issues worth of content, but 4 of them are counted as double, and so are labeled as such, so number 48 is labeled issue 52.

What I am looking for, is a better word to describe this issue than Double. Does anyone know a better word or phrase than double to describe this kind of thing?

Edit: As noted above, some people brought up that Double issue by default means exactly what was described. While I did not know that, It does not change my original intent, looking for a substitute word or short phrase that could also be used to describe this to others without the built in deception of Double. Another note, words that imply "once every two weeks" like Biweekly, do not fit this description. Shonen jump specifically is a Weekly Magazine, so using words like Biweekly to describe any of its Issues does not fit at all. The word/Phrase could likely also be a substitute for Leap in Leap Year. Though, If we can't find a good intuitive word/phrase, Leap might actually work.