diff --git a/raiss/windows.py b/raiss/windows.py
index aafa978af9d4076e4dc9a168962bb83f9882a703..893eb053641a884c2bdea38106fe21ba139e5e9b 100644
--- a/raiss/windows.py
+++ b/raiss/windows.py
@@ -32,7 +32,7 @@ def realigned_zfiles_on_panel(ref_panel, zscore):
         - ref_panel (pd.dataframe) : snp of reference on the imputed chromosome
         - zscore (pd.dataframe):
     """
-    inter_id = zscore.index.intersection(ref_panel.index)
+    inter_id = zscore.index.intersection(ref_panel.index).unique()
     zscore = zscore.loc[inter_id]
     sub_ref_panel = ref_panel.loc[inter_id]
     print(sub_ref_panel.Ref_all)