If you take a look at the gatherer rulings to the ozolith the szenario with 2 ozoliths is mentioned. I would assume it’s the same as with one ozolith and one hardened scales.
“If you somehow control two copies of Ozolith, the Shattered Spire, the number of +1/+1 counters put on an artifact or creature you control is two plus the original number. Three Ozoliths add three, and so on.”
If you take a look at the gatherer rulings to the ozolith the szenario with 2 ozoliths is mentioned. I would assume it’s the same as with one ozolith and one hardened scales.
“If you somehow control two copies of Ozolith, the Shattered Spire, the number of +1/+1 counters put on an artifact or creature you control is two plus the original number. Three Ozoliths add three, and so on.”