# Considerations for multi-Region applications
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When building multi-Region Apache Kafka applications with MSK Replicator, keep the following in mind:
+ **Idempotent consumers:** Your consumers must be able to reprocess duplicate messages without downstream impact. MSK Replicator replicates data at-least-once, which may result in duplicates in the standby cluster. When you switch over to the secondary AWS Region, your consumers may process the same data more than once. MSK Replicator prioritizes copying data over consumer offsets for better performance. After a failover, the consumer may start reading from earlier offsets resulting in duplicate processing.
+ **Tolerate minimal data loss:** Producers and consumers must tolerate losing minimal data. Since MSK Replicator replicates data asynchronously, when the primary AWS Region starts experiencing failures, there is no guarantee that all data is replicated to the secondary Region. You can use the replication latency to determine the maximum data that was not copied into the secondary Region.