I've just started learning Houdini & it's awesome so far, however still being uncertain of its intentions not sure how to use it for animation.

I've tried creating 2 Pyro sims (both Billowy Smoke) and both outputs are rendered ok but getting only 1 sim, so just a duplicate output. At this point I'm guessing the intention is to export the final sims / renders for compositing elsewhere ?

If you use same source and identical dop settings for both sim, you will get the same.

How did you created pyro sim? Did you used two different DOP Networks?

Post your file to check what's wrong in there.

With just a sphere & the Billowy Smoke.

I noticed after I posted this thread, that there were 2 sims merged within the pyro_sim. I think I need to randomise a seed because they're both identical.