From 6897536317c813917605c12568b5a70cdcb9848c Mon Sep 17 00:00:00 2001
From: Scott Sanderson <scoutoss@gmail.com>
Date: Thu, 6 Aug 2015 11:11:54 -0400
Subject: [PATCH] DEV: Raise useful error if we get dupe assets.

---
 zipline/modelling/engine.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/zipline/modelling/engine.py b/zipline/modelling/engine.py
index 579eb97b..911e5bc3 100644
--- a/zipline/modelling/engine.py
+++ b/zipline/modelling/engine.py
@@ -325,6 +325,10 @@ class SimpleFFCEngine(object):
         )
         assert lifetimes.index[extra_rows] == start_date
         assert lifetimes.index[-1] == end_date
+        if not lifetimes.columns.unique:
+            columns = lifetimes.columns
+            duplicated = columns[columns.duplicated()].unique()
+            raise AssertionError("Duplicated sids: %d" % duplicated)
 
         # Filter out columns that didn't exist between the requested start and
         # end dates.