I don't think it matters an ounce on Penta wheels - the design is 99.9% identical and on the 8J versions, offsets are also identical.
Penta versions also take the genuine AMG centre caps.
So with the only notable difference being 'PENTA' homologation instead of 'AMG', unless you're restroing an original AMG car, in my opinion/experience, little point in worrying about whether genuine or not.
cheers
talbir