For 36 years I have maintained that the way to tell original bundt style alloys from after-market copies is the radius on the inside of the rim.
I just bought a job lot of alloy wheels and am surprised to discover that I have 4 rims with Mercedes part number 1084001002 but two have the radius I would expect and two have the harder radius that I always thought were copies. I cannot discern any manufacturer's markings but I guess that MB must have used two different suppliers for these rims.
Mind you, I suppose it's not inconceivable that the copies could have also used a MB part number illegally.