99.8% of all matter by count is either hydrogen or helium, are atoms dimorphic?
If it were possible for us to exist (and thus consider the question) in the absence of the other atoms, and if those other atoms overwhelmingly (somehow) had a number of nucleons between 1 and 2, then the analogy might plausibly make sense.
That’s a very fun way to think about it, but it’s far more effective in a semantic debate than a serious one. I also don’t for a minute believe that the goal here is some broader reform of how the world talks about statistical distributions.
I’d rather not have discussions in bad faith.
If you're a cosmologist ;) usually they talk of 3 elements though - H, He and "metal".