Puzzle #115 - By the Dozen (Doppelblock)

I decided to try to make a larger Doppelblock today. After a few constructing dead ends, I managed to find this one.

puzz.link interface

For the interested solvers, it turns out that if you change the 4 to a 5, then the column 1 clue is unnecessary. However, I wasn't able to find a solution without casebashing on that version, and the only easy fix gave away a lot more information, so I tried a 4 instead.