It's one of those odd things you come across with the Germans. About a decade ago....the Germans were all enthusiastic about helping the poor Iraqis, who wanted asylum in Germany.
So, there was this one brief episode to occur where the Iraqi (naturally a Muslim) had two wives, and wanted asylum. A Pfalz court got involved and finally determined as part of the asylum process.....if indeed a guy was married in his home country to two wives (had to be a valid marriage, probably paperwork, I imagine), the the first wife got a residence permit, and the second wife would be shown "tolerance for several years" with a residence permit as well. Nothing in the court document 10 A 11717/ 03.OVG shows a divorce required, and one would assume that the guy just keeps going for the rest of his life, in Germany.....with TWO wives.
A review later and some tolerant method to separate the second wife? No, the court of the state of the Pfalz simply said that the second would have several years of German tolerance. Social security pension via the husband to both wives? You'd have to take a wild guess that it'll come up as both wives apply and this 10 A 11717/03.OVG rule will open the door for that.
More or less, the German court system has already stepped into the religious political question and taken more than a step or two.
What keeps a German guy from journeying to the Middle East and marrying two German women, then returning to cite the same code and demand that the German government recognize multiple marriages? Only the fact that no one has grasped this gimmick yet to force the issue.