Turns out that wordpress uses context strings for this piece of text:
_x(‘Add New’, ‘post’) and _x(‘Add New’, ‘page’)
This is because the string ‘Add New’ is different depending on the following noun in some languages. i.e in Danish:
‘Add New Post’ => ‘Tilføj Nyt Indløg’
‘Add New Page’ => ‘Tilføj Ny Side’.
Notice the added ‘t’ in ‘Nyt’.
Might be helpful to others.