Hi George,
Thank you for the question.
So the behaviour you are seeing is highlighted here in this known limitation, https://docs.developers.symphony.com/building-bots-on-symphony/messages/overview-of-messageml/symphony-elements-1#known-limitations
So there are a couple of options to address this which are detailed below.
Option 1.
To ensure forms are not re-submitted you would need to store the 'form-id' and the userId values in a datastore. Your bot application can then determine if the form was already submitted or not. The structure of the payload can be found here, https://docs.developers.symphony.com/building-bots-on-symphony/messages/overview-of-messageml/symphony-elements-1
Option 2.
Another option is to use the Message Update feature to disable the form once the first reply has been received.
Hope that helps.