diff --git a/simulator/serial.py b/simulator/serial.py
index 61c3f3d..eea9494 100644
--- a/simulator/serial.py
+++ b/simulator/serial.py
@@ -5,22 +5,35 @@ import string
 
 class Serial:
 	def __init__(self, path, baudrate, timeout):
-		self.path     = path
-		self.baudrate = baudrate
-		self.timeout  = timeout
+		self.path       = path
+		self.baudrate   = baudrate
+		self.timeout    = timeout
+		self.generated  = set()
+		self.exceptions = True
 
 	def gen_key(self, count):
 		lst = [random.choice(string.hexdigits) for n in range(count - 2)]
-		return "A" + "".join(lst) + "D"
+		ret = "A" + "".join(lst) + "D"
+		print("> Serial generated key: %s" % ret)
+		self.generated.add(ret)
+		return ret
+
+	def old_key(self, count):
+		if len(self.generated) == 0:
+			return self.gen_key(count)
+		index = random.randint(0, len(self.generated) - 1)
+		ret = list(self.generated)[index]
+		print("> Serial using old key: %s" % ret)
+		return ret;
 
 	def read(self, count):
-		val = random.randint(0, 4)
-		if val == 0 or val == 1:
+		val = random.randint(0, 5)
+		if val == 0:
+			return self.gen_key(count).encode()
+		elif val in {1, 2}:
+			return self.old_key(count).encode()
+		elif val in {3, 4} or self.exceptions == False:
 			return "".encode()
-		elif val == 2 or val == 3:
-			ret = self.gen_key(count)
-			print("> Serial generating key: %s" % ret)
-			return ret.encode()
 		raise Exception("Test Serial Exception")
 
 	def flushInput(self):
diff --git a/simulator/urllib/request.py b/simulator/urllib/request.py
index 8efdc67..ced816c 100644
--- a/simulator/urllib/request.py
+++ b/simulator/urllib/request.py
@@ -13,11 +13,11 @@ class Request:
 		pass
 
 	def read(self):
-		val = random.randint(0, 4)
-		if val == 0 or val == 1:
-			return "OK".encode()
-		elif val == 2 or val == 3:
+		val = random.randint(0, 5)
+		if val == 0:
 			return "ERROR".encode()
+		elif val < 4:
+			return "OK".encode()
 		raise Exception("Test Network Exception")