**“Where life is more common; is that feasible?”**

Yes, in an alternate Universe, you have pretty much complete liberty as a writer.  Your alternate universe could even have alternate physics.  It’s literally your world to decide what you want to do with.

**Would it be plausible?**

Yes, it could be very plausible.  In an alternate Universe with more worlds in the Goldilocks Zone, this would mean more worlds that could support life.  And certain forms of life can expand very rapidly.

**As the writer, you just need to sell it**

This is somewhat of a frame challenge, but this is my answer for you.  Because you are dealing with an alternate universe, you have pretty much complete authorial liberty.  Just make sure and see it well to your readers.  Explain that life grows and replicates at a higher rate in this alternate universe.  Perhaps twins/triplets are far more common in this universe, and are actually the expected norm.  You’ve got this.