You may be able to get away with it on a low-speed road, but it's a dangerous design on high-speed roads.

It is highly discouraged in my area simply because it causes issues with safely plowing snow off the road.

I've seen it done on occasion where modifying the existing pavement was going to be cost prohibitive.

My personal preference would be to modify and re-sheet the whole road if required to suit the new lanes configuration.

In a quick search, I couldn't find any safety research on the question, probably because it's not very common. The problem would be drivers changing lanes and crossing the crown line. The sudden change in steering angle needed as the vehicle crossed over would be noticeable and disconcerting at the very least.

On a low speed tangent, it might justifiable as a non-conforming feature. On a curve or at higher speeds, I'd recommend against it.