Jumeaux was a Darkover fanzine edited by Lynne Holdom. The first issue was published in November, 1977 and after that, the fanzine appeared quartely in February, May, August and November each year until November 1981, when issue #10 was published.
In 1981, Holdom started to publish the Jumeaux Definitive Edition, where she reprinted material from earlier issues. The run of the Definitive Edition is unclear, but at least four issues were announced and published. The sporadic and rather bewildering numbering system makes it very hard to follow the run of the Definitive Edition: apparently, Definitive Edition #4 was the first issue published in Janurary 1981, followed by #4 in May 1981, #1 in October 1981 and #2 in March 1982.
Jumeaux #5, the World Wreckers Inc. issue was published in March 1983. Jumeaux #9, the Stormqueen issue came out in August 1983 and Jumeaux #6, the Forbidden Tower issue in January 1984. Jumeaux #10, the Two to Conquer issue, was published in June 1985. It is not indicated in the fanzines, whether these issues were part of the Definitive Edition or not. The erratic and inconsistent numbering and dating systems seems to suggest that they were.
An unnumbered issue came out in August 1982 and it is not clear whether it belonged to the fanzine's original run, or to the Definite Edition. If it was part of the original run, following the normal quarterly time table it would've been issue #16. If it was part of the Definitive Edition, it could have been Definitive issue #7 or #8 or some issue beyond #10.