I bought a Decklink Duo 2, but resolume only shows the options to select the resolution in the first two outputs, in the third and forth only lets select but no options, is this normal?
Oaktown pointed me to this excellent article that explains about port mapping on a Quad2 card. Apparently the same goes for a Duo2.
Long story short, by default the four output channels are mapped to two SDI outputs, and two SDI outputs are "unused". You'll need to change this in BM's setup software and the article explains how.