module.exports overwrite

index.js

require('./rand')()();
require('./rand')()();
require('./rand')()();
require('./rand')()();
require('./rand')()();
require('./rand')()();
require('./rand')()();

rand.js

module.exports = function() {

    module.exports = function() {
        var fn;
        var rand = Math.floor((Math.random() * (4 - 1) + 1));
        switch (rand) {
            case 1:
                fn = function() {
                    console.log('1111')
                };
                break;
            case 2:
                fn = function() {
                    console.log('2222')
                };
                break;
            case 3:
                fn = function() {
                    console.log('3333')
                };
                break;
        }

        return fn;
    };

    return function() {
        console.log('STABLE');
    };
}