I've 2 separate conversations with 2 different contacts (not the same phone number, nothing in commun).
On my MacBook (High Sierra) everything works fine.
But on my iPhone X running iOS 12 beta 3 (since beta 2 I've this bug), these 2 conversations are merged.
When I write to one or another of these 2 contacts, it displays the 2 conversations in one screen. It merges them.
When I try to create a new message, when I enter one of the 2 contacts, I don't know who receive the message, it's not always the same one that receive the message.
That's really annoying.
Does anyone have this issue too?
I filled a bug reporter for that.