two languages - modul itemid does not change

I suppose that you must be using joomla 2.5's multi language system.
It doesn't allow you to change the itemid when you switch the language.
And the way it's done, I don't see how you can do that.

If you use instead Falang's multi language capabilities, you can have the same module in several languages, that way you don't have that itemid problem because with it you translate directly one module in the different languages instead of having to create one module per language like you do with Joomla.