Just because there's a sequel doesn't mean the first movie did well. House if the Dead 2, Bloodrayne 2, Boogeyman 2, Wrong Turn 2, I could go on.
These actually sold well enough to make a profits. Wrong turn has 4 movies in the franchise along with a 3 pk of the 1st ones. zombie movies have a cult following + people that just buy any old zombie flick for dumb fun(my GF loves wack horror flicks but has never seen the goonies, A-Team(series), Knight(series) & doesn't even know who Clint Eastwood is:roll:). Those movie collections in Walmart actually sell well & look at the # of walmarts that carry them, you'll see people grab 4-10 movies at a time just to have something to watch eventually there's no "good" movies so these trickle in.
Bloodrayne franchise is way limited since it's nothing like the Tomb raiderr franchise but my guess is that the game company backed it to help split the cost.