When you include a file inside a module definition, all the contents of that file is loaded into the module scope. So, you have modules Main.ModuleA.MyParams and Main.MyParams, which the system considers different.
There have been discussions recently on how to organize code in such cases, you may find and try different suggestions to choose from:
(Writing functions for types defined in another module)
(What is the preferred way to use multiple files?)
Also, please see this topic (Please read: make it easier to help you) for tips on formatting.