patch_proposal.patch

--- simulations/engine.py
+++ simulations/engine.py
@@ -16,11 +16,18 @@
         self.y_t_no = 0.0

     def cast_vote(self, agent_id, amount, vote, current_epoch):
-        self.votes[agent_id] = {
-            "amount": amount,
-            "epoch_staked": current_epoch,
-            "vote": vote
-        }
+        if agent_id in self.votes:
+            if self.votes[agent_id]["vote"] != vote:
+                self.votes[agent_id]["epoch_staked"] = current_epoch
+                self.votes[agent_id]["vote"] = vote
+
+            self.votes[agent_id]["amount"] = amount
+        else:
+            self.votes[agent_id] = {
+                "amount": amount,
+                "epoch_staked": current_epoch,
+                "vote": vote
+            }

     def update_conviction(self, alpha, t_max, current_epoch):
         v_t_yes = 0.0