These indices are what we call replicas. Replica indices are generated when you set sorting strategies: https://community.algolia.com/magento/doc/m2/indexing/#sorting-strategies
In Algolia, every index has a unique sorting strategy, which is statically defined at the index level. Pre-sorting at index time instead of at query time leads to a huge performance boost. Consequently, if you need different ranking formulas depending on the use case, you need one index per ranking formula.
You can read more about it in our docs: https://www.algolia.com/doc/guides/ranking/sorting/
Replicas aren’t exact duplicates: the data is the same, but the ranking is different.
In your case, you probably have set different sorting strategies in your Magento admin, which explains why you’re seeing those replica indices in your Algolia dashboard.
If you disable your sorting strategies, the associated replica indices will disappear.
Have a nice day!