Both of the cultures do different things in your gut. In this case, inhabit different zones of the small intestine. If you do them both, together, you do not have to do them one-by-one. My first batch of one of them came out all separated, but when combined the both of them came out smooth with the consistency of Greek yogurt.
I have been around long enough to look into many different things.

Rothbardian_fanatic

You are a man of many interests!

What’s the advantage of making yoghurt from two different cultures? 

cryotosensei

science

Gut Microbes and Host Physiology: What Happens When You Host Billions of Guests?

south_korea_ln

I don’t have any recipes for yogurt. You have to get either some from someone that has it or buy L. Reuters and L. Gasseri starter packs from Cutting Edge Cultures. You will also need some prebiotic fiber. The recipe can be found here:
https://www.culturedfoodlife.com/recipe/l-gasseri-superfood-yogurt/

I made two different cultures than combined them in a later batch. I just make more from the previous batches.