There are two uses of the word "Mini" going on here. The OP used both but his actual question had to do with mini versions of an existing product. The only pair I own are the Mad Hatter clones and they're made by different companies. One by EHPro, the other by Tobeco, I'd need to find the little boxes, or dig in to see where I bought them to find out which is by who. That said... oddly the Minis have a deeper well than the full size. But they made the posts shorter (for the shorter top cap) and that may have allowed the space to keep the interior bottom lower and the inner rail higher. Dunno. Glad for it though.
Someone with matched authentics or even clones can address whether they sometimes change the design when they shorten the height.
My well comment above though, had to do with the generic use of "Mini"... that being the tiny originals like the Derringer, the Lepton and Mikro mentioned upthreaad, I have a little Bonsai that might count. I meant it would be nice to keep the well as deep as possible (or in some cases... existent at all) on the tiny RDAs.
Sometimes it can be done, sometimes it can't.