Starting with CU13 of SQL Server 2019 , we are including new functionality which facilitates peer-to-peer replication with conflict detection & resolution using a last-writer-wins strategy. This enables many scenarios for multi-write configurations which may not have been possible or practical before.
Traditionally, customers configuring peer-to-peer replication are advised to implement a sharded solution which ensures that each row is updated on only one replica server (key values A-M are updated on server 1 while key values N-Z are updated on server 2, etc.). If it should happen that the same row is updated within a small time window by two servers in a replication environment, a conflict will be detected, which will either stop replication after raising an error, or it may optionally be resolved using the originator ID of the replica sending the update. (i.e. if you have replicas with Originator IDs 1 and 2, then updates coming from the replica with originator ID 2 would always win, and be persisted. See Conflict Detection in peer-to-peer replication – SQL Server | Microsoft Docs for a detailed explanation.
Read on for more details.