I bought the OVP from FastLane for my 300E and it had the two slots for fuses (like the OEM one). It uses one fuse, though.
The "crappy" unit was found to be defective many moons ago, and has been displaced from Mercedes parts shelves everywhere (except for some shady operators).
You can rest assured that your OVP is fine.
If you want to verify that you have a good one, the "bad" OEM unit would have the "Seimens" (Austria) notation on the case. Replacements do not...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car