At the moment there is no Fluent API for dynamic modules. The modules you create with the Module Builder are dynamic modules. When you create such a module a code reference is generated. You can use it freely with the native API.
You could get all the items from the first module and all the items from the second module and add then to a list for example.
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items