I have an array of arrays, which looks something like this:
[[\"Some string\", \"Some other string\"],[\"Some third string\", \"some fourth string\"]]
Why not intersection? (if you really want to use some Underscore functions for this) http://underscorejs.org/#intersection
If the arrays are of the same length, and the length of the intersection equals to the length of the arrays, then they all contain the same values.