The S4S WFFM Module can be configured to be able to submit data to multiple Salesforce Orgs on a form-by-form basis. Currently, this is only available for S4S with Sitecore 8.1 onwards.
Sitecore 8.
...
1 Onwards Configuration
The multiple S4S connection strings are configured in the App_Config/ConnectionStrings.config file. By default, you need to configure the S4SConnString and S4SConnStringUI.
...