Dear Pascal,

The View layer is usually independent from login.

However, if you have created a custom view for a user, it will be understood that you have overridden fields_view_get() or load of action from web.

Usually, you should link the view to the Purchase Order action. If you want separate view fo separate user, you must create 2 actions, bind the specia view to the special action.

Another solution would be to use same view, but hide/show specific fields based on User's group.

Hope this helps.

Thanks.