In Node.js, why are variables equal the same across modules using the require function?

I have the following files in the same directory:

data.js

var anArray = [1,2];
module.exports = anArray;

mod1.js

var data = require('./data');
module.exports = data;

mod2.js

var data = require('./data');
module.exports = data;

main.js

var mod1 = require('./mod1');
var mod2 = require('./mod2');

When I do mod1 === mod2 it is true Why is that? My initial belief was that mod1 and mod2 files should contain an array but that are different (different references to the array objects).