diff --git a/notebooks/data/births.csv b/notebooks/data/births.csv
index 4a5bb7ae..ebd16ae5 100644
--- a/notebooks/data/births.csv
+++ b/notebooks/data/births.csv
@@ -3,9 +3,7 @@ year,month,day,gender,births
 1969,1,1,M,4440
 1969,1,2,F,4454
 1969,1,2,M,4548
-1969,1,3,F,4548
-1969,1,3,M,4994
-1969,1,4,F,4440
+1969,1,3,F,1969,1,4,F,4440
 1969,1,4,M,4520
 1969,1,5,F,4192
 1969,1,5,M,4198