Luminate allows multiple milestones to be set at the same achievement amount. When it's set up this way, it may cause duplicate achievement autoresponders to be sent. The system appears to choose one of the milestone autoresponders and sends it multiple times depending on how many milestones exist at the same fundraising amount.
We are currently evaluating this issue and will update this article when we have more information. In the meantime, you'll want to disable the autoresponder delivery for the other milestones or disable the other milestones completely, so that only one is sent. Be advised that using the same achievement amount for autoresponders is not recommended. Luminate uses the achievement amount to determine the highest milestone achieved. The system can't do this easily when multiple milestones exist with the same achievement amount. Doing so will cause issues such as this.
Steps to Duplicate
Create 2 or more milestones with the same achievement amount.
Enable the milestone autoresponder in each milestone.
Type in some unique content in the milestone message content area, like "This is milestone 1" - "This is milestone 2"
Register for the event and create an offline donation to achieve that amount.
You will receive 2 or more of the same autoresponder.