This addresses an issue where:
• someone would create a closed group
• on other peoples' devices this control message would be received through a background poll or a push notification
• the received message timestamps table would be updated
• processing wouldn't be finished (during a background poll or while handling a push notification the system can cut you off at any time)
• some of the added users don't see the new closed group because when they open the app and get the control message from their swarm it's considered a duplicate and isn't processed again
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