Pokin' around code I shouldn't be pokin' around

gistfile1.txt

diff --git a/interface.js b/interface.js
index 89a7c2c..aef728b 100644
--- a/interface.js
+++ b/interface.js
@@ -41,6 +41,7 @@ var PerseusBridge = Exercises.PerseusBridge,
     numHints,
     hintsUsed,
     lastAttemptOrHint,
+    lastAttemptContent,
     firstProblem = true;
 
 $(Exercises)
@@ -128,6 +129,7 @@ function newProblem(e, data) {
     numHints = data.numHints;
     hintsUsed = data.userExercise ? data.userExercise.lastCountHints : 0;
     lastAttemptOrHint = new Date().getTime();
+    lastAttemptContent = null;
 
     var framework = Exercises.getCurrentFramework();
     $("#problem-and-answer")
@@ -192,11 +194,21 @@ function handleAttempt(data) {
         canAttempt = false;
     }
 
-    var curTime = new Date().getTime();
-    var timeTaken = Math.round((curTime - lastAttemptOrHint) / 1000);
-    var stringifiedGuess = JSON.stringify(score.guess);
+    var curTime = new Date().getTime(),
+        millisTaken = curTime - lastAttemptOrHint,
+        timeTaken = Math.round(millisTaken / 1000),
+        stringifiedGuess = JSON.stringify(score.guess);
+    
     lastAttemptOrHint = curTime;
 
+    // If user hasn't changed their answer and is resubmitting w/in one second
+    // of last attempt, don't allow this attempt. They're probably just
+    // smashing Enter.
+    if (stringifiedGuess === lastAttemptContent && millisTaken < 1000) {
+        return false;
+    }
+    lastAttemptContent = stringifiedGuess;
+
     Exercises.guessLog.push(score.guess);
     Exercises.userActivityLog.push([
             score.correct ? "correct-activity" : "incorrect-activity",
@@ -362,6 +374,7 @@ function onHintShown(e, data) {
     var curTime = new Date().getTime();
     var timeTaken = Math.round((curTime - lastAttemptOrHint) / 1000);
     lastAttemptOrHint = curTime;
+    lastAttemptContent = null;
 
     Exercises.userActivityLog.push(["hint-activity", "0", timeTaken]);