diff --git a/docs/freqai.md b/docs/freqai.md
index 821f42258..78e25a234 100644
--- a/docs/freqai.md
+++ b/docs/freqai.md
@@ -400,7 +400,7 @@ The user can stratify the training/testing data using:
     }
 ```
 
-which will split the data chronolocially so that every X data points is a testing data point. In the
+which will split the data chronologically so that every X data points is a testing data point. In the
 present example, the user is asking for every third data point in the dataframe to be used for 
 testing, the other points are used for training. 
 
diff --git a/freqtrade/freqai/data_kitchen.py b/freqtrade/freqai/data_kitchen.py
index 63420a52b..45131f3d0 100644
--- a/freqtrade/freqai/data_kitchen.py
+++ b/freqtrade/freqai/data_kitchen.py
@@ -715,10 +715,9 @@ class FreqaiDataKitchen:
 
         exchange = ExchangeResolver.load_exchange(self.config['exchange']['name'],
                                                   self.config, validate=False)
-        pairs = self.freqai_config.get('corr_pairlist', [])
-        if metadata['pair'] not in pairs:
-            pairs += metadata['pair']  # dont include pair twice
-        # timerange = TimeRange.parse_timerange(new_timerange)
+        pairs = copy.deepcopy(self.freqai_config.get('corr_pairlist', []))
+        if str(metadata['pair']) not in pairs:
+            pairs.append(str(metadata['pair']))
 
         refresh_backtest_ohlcv_data(
                         exchange, pairs=pairs, timeframes=self.freqai_config.get('timeframes'),