Multiple Loki different inctances send to same bucket

Please see my reply to another topic here: Loki 2.4.1 empty ring Code(500) error for "GET /loki/api/v1/labels" API on AWS ECS - #10 by tonyswumac

It doesn’t directly apply to you (unless you are using ECS as well), but I did explain how service discovery works and how memberlist ring is configured there.