"...was set...this setting...is set" <= etoomanysets, and in general, these first two paragraphs dive into technical details without setting any business context.

Suggested text for first two paragraphs (please mangle to suit): Prior to Riak 2.0, Riak did not creating siblings for conflicting updates unless configured otherwise via `allow_mult`. With 2.0, this is still true for the `default` bucket type, but for newly-created bucket types and the buckets contained therein, `allow_mult` will be set to `true` unless configured otherwise.

This means that applications which have previously ignored conflict resolution can continue to do so, but new applications are encouraged to retain and resolve siblings with appropriate business logic.

(and then dive into some techie stuff)