Does the model and the controller share a 1to1 relatioship?

No, there is no forced relationship between controllers and models.

The issue with multiple scaffolds in the controller is that you get
duplicate action names generated. But you can do it with a :suffix

From the API docs for the scaffold method:

"It's possible to use more than one scaffold in a single controller by
specifying options[:suffix] = true. This will make scaffold :post,
:suffix => true use method names like list_post, show_post, and
create_post instead of just list, show, and post. If suffix is used,
then no index method is added."