When you hash an already hashed file, the file reference is not replaced in the dest

tasks/filecache.json

@@ -0,0 +1 @@
+{}

tasks/hashresHelper.js

@@ -29,7 +29,9 @@ function preg_quote (str, delimiter) {
 }
 
 exports.hashAndSub = function(grunt, options) {
-
+  //We open the cache file, and then JSON decode it.
+  var fileCache = JSON.parse(fs.readFileSync(path.resolve(__dirname, 'filecache.json')));
+
   var src              = options.src,
       dest             = options.dest,
       encoding         = options.encoding,
@@ -71,11 +73,22 @@ exports.hashAndSub = function(grunt, options) {
         var destContents = fs.readFileSync(f, encoding);
         for (var name in nameToHashedName) {
           grunt.log.debug('Substituting ' + name + ' by ' + nameToHashedName[name]);
-          destContents = destContents.replace(new RegExp(preg_quote(name), "g"), nameToHashedName[name]);
+          if (fileCache[name]) {
+            //If the file was already hashed, and it has a wierd name like style.df23d23.css, then replace that name instead of the original name.
+            grunt.log.debug('File was already hashed');
+            destContents = destContents.replace(new RegExp(preg_quote(fileCache[name]), "g"), nameToHashedName[name]);
+          } else {
+            //If the file has not been hashed before
+            grunt.log.debug('File is new');
+            destContents = destContents.replace(new RegExp(preg_quote(name), "g"), nameToHashedName[name]);
+          }
+          fileCache[name] = nameToHashedName[name];
         }
         grunt.log.debug('Saving the updated contents of the outination file');
         fs.writeFileSync(f, destContents, encoding);
       });
     });
+    //Save the cache file with the new mappings
+    fs.writeFileSync(path.resolve(__dirname, 'filecache.json'), JSON.stringify(fileCache));
   }
 };