I see quite a lot of these fishy ebay articles on ebay.de; they will have S905 or S905X as part of the name or heading, but will list the correct processor in the small print at the end of the listing. Mostly it is RK3229 boxes that are "SEO-ed" with the S905 tag. Some of these "enhanced" listings are harder to spot than others, and I can understand that an unaware buyer might easily be fooled.
I had one of these boxes here - but in that case the seller even stated in the description that it is indeed an amlogic S905. Well - it wasn`t.
It won`t let you install any app from the playstore to confirm your doubts, nor can any information about the internals be found anywhere.
Fraud, if you ask me.
Had to sideload aida to confirm it`s a rockchip box.