What is the Duplicate Draft feature?
Mobile users have in the past been able to clone a form draft saved on their mobile device, creating a second identical draft.
Why is the feature being deprecated?
We've decided to retire this feature for two reasons.
First, the feature has caused support issues for too many customers. For example, a cloned draft that submits to SharePoint can overwrite a submission by the original draft, causing the original instance to seem to disappear from SharePoint. Another example: Cloning a draft that contains a signature can undermine the trust in signatures.
Second, the feature is no longer needed. The original reason for the feature was to create a handy way for mobile users to avoid tediously re-keying the same information into every new form. We have since introduced new ways to accomplish that goal using buttons and links. See: How to transfer data form-to-form for a method to open one form from another form and pass data to it. This allows the form designer to offer users the convenience of opening partially pre-filled forms.
What if an organization wants to continue using the feature?
If your organization is currently using this feature there is an option to continue using it longer while you transition to new best practices. For now the feature will be turned off by default, but the owner of your organization can change the setting to turn it back on. You can expect the feature to be completely removed in 2016.