Chimney Connection/Modified Wall Thimble

I bought a stove from another individual, complete with double-wall chimney pipe and a thimble kit to go through the wall. (DuraPlus by DuraVent, 10" OD/6" ID.) After the handyman and I finished installing the flue, we figured out that the wall thimble has been modified. This is what it looks

ALLFUEL HST 6 in. x 12 in. Wall Thimble for Double Wall Chimney Pipe BL.EV.RB-SHT6WT-P - The Home Depot

Safe Through The Wall Stove Pipe Installation, 44% OFF

Safe Through The Wall Stove Pipe Installation, 44% OFF

What am I dealing with here to connect to this chimney support box? : r/woodstoving

Wall Thimble Installation

Exhaust Thimble Installation Guide

The 6 Class-A Wall Thimble is used for through-the-wall chimney installations. It protects the wall as the chimney passes safely through to the outside and provides a finished look to the framed opening on the inside. The Wall Thimble can adjust to accommodate walls from 6 to 10 inches thick.

Allfuelhst Wall Thimble for 6 inch Diameter Chimney Pipe

What Is A Chimney Thimble

Going To Put A DuraVent Chimney In, Here's My Plan And A, 54% OFF

Connecting Duravent Chimney Adapter to Existing Masonry Chimney Thimble Pipe