The phrase "double viewpoint of" is correct and usable in written English
You can use it when you want to refer to two perspectives or opinions on a single topic. For example, "The double viewpoint of management and labor was critical to the successful negotiations."
Of the three books, I would have to say that Allegiant is probably my favourite, purely because I liked the double viewpoint aspect and the widening of the characters' world.
In places, the switching between viewpoints got a little hazy and the two narrative voices sounded too similar to the point where it was confusing to read, but other than that the double viewpoint really worked.
In fact, consideration of possible outcomes reveals that macrophage cell division is potentially a double-edged sword from the viewpoint of host defense mechanisms.
A new type of double-stage absorption heat transformer integrated with water desalination system is proposed and compared with four other types of absorption heat transformers i.e. a conventional type of double-stage and three different types of double-effect absorption heat transformers from the viewpoint of exergoeconomics, using Engineering Equation Solver software.
The possibility of double-layer repository is analyzed from the viewpoint of the thermal constraints of the repository.
For me, this meant taking on the exciting viewpoint of limitless resources: we should double down on extraction technology, invest in new wells, fracking, and mining, with an end goal of bringing health, wealth, and conspicuous consumption to the planet.
"Not from the viewpoint of salary".
His viewpoint of it was positive.
From the viewpoint of historic preservation, this makes no sense.
A — From the viewpoint of enlightened self-interest.
