Creating a view with 2 content of different content types
"2 specific contents" .. if it's very specific / admin decides, add an extra field with code. Fill 2 nodes with something like 'promo' or '1234 Hide this field in the display, so you only see the code when you're editing. In the view, filter on this field (only nodes with this and this code) and voilá. 

-edit: in this way you can re-use the view for different codes. Maybe use the URL (like foobar.com/promo shows the 2 nodes with promo in the code field). Tbh, i don't know how to use the URL in Views ;-)