Mint organisation under the Gallic Emperors:
Personally, I would regard the Theory of Marcus Weder as the most convincing:
Under Postumus only one Mint worked, opened 260 AD at Cologne. A second mint had been opened under Marius 269 AD, maybe located at Trier. These two seperate mints worked during the reign of Victorinus, and have been reunited under Domitianus II (location of the mint undetermined). The once seperate mints now worked as branchs side by side until the end of the reign of the Tetrici, which is prooved by several "cross-mint-hybrids".
The Theory of E. Besly, R. Bland and E. Burnett differs in some points:
Under Postumus, first one mint worked, located at Trier, opened 260 AD. 268 AD, a second mint opened at Cologne, proved by the emission of the Reverse Types COL CL AGRIP COS IIII, C C A A COS IIII, and IOVI VICTORI C/A. These two seperate mints worked during the reigns of Laelianus, Victorinus and Domitianus II. At the end of the reign of the Tetrici, the mints were reunited again.