We have similar use cases in which we would like to have multiple forms on the same page.
One use case for is creating/editing questionnaires (CPT: questionnaire) with multiple questions (CPT: question).
Cloneable fields will not be an option for us in these cases.
Would it be possible to think about implementing this feature, for instance by creating unique ids for the different forms, instead of using the meta_box id's to generate the form id?
We have worked a lot with toolset (toolset forms) and they used to have the same issue... but after some feature requests they made this possible.
Cheers,
Tako