Diamond Select Toys makes a stylized series of simple figures called "Minimates" for several franchises characters. At Toyfair 2018, they added Sonic to their list with this Mini Mates display here. The card says they intend for these to be a box set of some type. It's also marked with 'series 1', so if it does well that generally shows intention to make another set adding more characters.
They have a bit of a curious starting line-up though, with who they chose here.

They skipped Knuckles & Shadow, but included Silver & Cream. (An uncommon decision) There's even a chao in their style! But, with it turned away you can't tell if it's Cheese. In this style, all characters are somehwat 'lego figure like' with obviously rectangle bodies with no real shape, painted on body detail & basic cylendrical heads. This works better for some characters than it does for others...and they break their own rule somehow with Eggman? Why? Most of the characters look ok, except for Cream who's head seems way too small & body too big with very long legs. She's supposed to have 'babyish' proportions, but....it's just not happening here.
Hopefully these can get some refinement before they're released. Better photos will appear here once they're released. 

The first photo on this page shows the Minimates at Toyfair.
But in the gallary is a photo that shows their release in 2019 (so about a year) in the 4 pack that they promised. You get Sonic, Amy, Tails & Eggman in one pack, plus 2 small brown rings. Sometimes you'll see the pack with the central part covered by a card or a sticker to hide the "2nd body" for Tails.
Why?
It's not another body, it is actually a type of "Smock", with his tails attached & the white patch printed on the front. You have to pull his head off, and snap this extra piece down over the body you see on the figure, in order to complete him. It was done this way so that everything would fit in the box properly because his tails are big. So, he is not missing details or wrong, or duplicate, it's just packaging mechanics and how they solved it.
Info provided by: Taaron