Email reply request ID double up

Email reply request ID double up

Hi there,
When replying to a ticket the request ID is added in the subject so that when they reply to it SD+ knows what ticket it belongs to.

But when I reply to their reply, the request ID is added again along with the subject (which now includes the request ID) so the longer the conversation the more request IDs get added.

Have we set this up incorrectly?
See screenshots

Cheers,
Nick

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