This warning will appear with the new version of Grasshopper (0.9.006) if you have more than one copy of the DIVA.ForGrasshopper.gha file saved on your computer. Unlike in the past, the new version of Grasshopper searches in many different places for assembly files. In our case, the assembly file is probably saved in both the following locations:
C:\Program Files (x86)\Rhinoceros 4.0\Plug-ins\Grasshopper\Components
You should delete one of the two files (preferrably the older one). If you plan on sticking with GH 0.9, I would suggest having the file only in C:\DIVA, as this location will get updated when you update DIVA, and you won't have to manually move the file to the Components folder anymore.