Along came the monsters and then I said to myself -- wait a minute, aren't these the same monsters that I had attack them earlier?
Consider the matter, and conclude, despite a handful of differences, that yes, they are basically the same monsters.
Which means I really need a third appearance. Something that appears twice and is left hanging is a broken pattern. (Unless it's bookends for the beginning and end.)
Let's see -- yeah, that can be the monster that bothers them there, as well.
Such is the life of a writer. Stories have a wonderful tendency to sprout motifs and need patterns for them.