Love that answer. Got my grin for the day. Thank you.

Many many years ago we lived in Germany and rented a furnished apartment in a family's home. The bed was king size, like 2 twins pushed together but they didn't come apart. The only cover was 2 very fluffy thick (maybe down) comforters in duvet covers. Neither of them hung off the side of the bed. Rather than covering the bed to make it, we folded each cover at the foot of the bed. I loved having the sheet and blanket all in one and neither of us hogged the covers because we each had our own. I have tried for years to find duvets like those, but to no avail.

We actually do the following: I have a king sized wool/bamboo batting quilt on the bed and then if we are still cold, we add a lap sized quilt on whomever is coldest.

A California King size bed is two twins put together. I would think two twins would work just fine

I was thinking the same idea! I'd love to see and feel one like this.

We just traveled to Ireland and all the hotels used duvets--neither of us liked them--too heavy! We use a sheet, light weight cotton blanket and quilt--and during really cold weather we'll add another quilt--which I usually kick off and my DH rolls up in.
Have you tried a wool bat in a quilt? Because it "breathes" it has a higher thermal rating, allowing it to adjust heat level.

Another horror story from a foreign country. We stayed in Japan one night on our way to Singapore. They had the twin beds, with duvets. No other sheet and no other blanket. The duvet cover must have been made of some heat retaining material because it got very hot under there, and when I would push it aside for a while, the room was really cold. I didn't sleep much that night. And it was not hot flashes either. LOL

Had the same issue here a few years ago. I had a store bought quilt-not one of our lovely handmade quilts....He was always throwing his side of the quilt onto my side and it was heavy on me. So, I decided to fix the issue the best way I knew how-I cut the quilt in half right down the middle. On his side I sewed half of a sheet and my side was half of the quilt. I called it He's Hot, She's Not. It worked.

We just got back 2 weeks ago from visiting our daughter in Iceland. The hotel we stayed at had 2 duvets folded up on each side of the bed. It was a little weird, but made a lot of sense since hubby & I each had enough duvet. And no one hogged all the bedding!

The Company Store in La Crosse Wisconsin has what you are describing. Good Luck
Suzy