diff --git a/lstchain/io/io.py b/lstchain/io/io.py
index a5d76e359a..ae1922442e 100644
--- a/lstchain/io/io.py
+++ b/lstchain/io/io.py
@@ -85,7 +85,6 @@
 dl1_mon_tel_CatB_ped_key = "/dl1/monitoring/telescope/catB/pedestal"
 dl1_mon_tel_CatB_cal_key = "/dl1/monitoring/telescope/catB/calibration"
 dl1_mon_tel_CatB_flat_key = "/dl1/monitoring/telescope/catB/flatfield"
-
 dl1_params_lstcam_key = "/dl1/event/telescope/parameters/LST_LSTCam"
 dl1_images_lstcam_key = "/dl1/event/telescope/image/LST_LSTCam"
 dl2_params_lstcam_key = "/dl2/event/telescope/parameters/LST_LSTCam"
@@ -304,6 +303,7 @@ def auto_merge_h5files(
         file_list,
         output_filename="merged.h5",
         nodes_keys=None,
+        keys_to_copy=None,
         merge_arrays=False,
         filters=HDF5_ZSTD_FILTERS,
         progress_bar=True,
@@ -319,6 +319,7 @@ def auto_merge_h5files(
     file_list: list of path
     output_filename: path
     nodes_keys: list of path
+    keys_to_copy: list of nodes that must be copied and not merged (because the same in all files)
     merge_arrays: bool
     filters
     progress_bar: bool
@@ -336,6 +337,8 @@ def auto_merge_h5files(
     else:
         keys = set(nodes_keys)
 
+    keys_to_copy = set() if keys_to_copy is None else set(keys_to_copy).intersection(keys)
+
     bar = tqdm(total=len(file_list), disable=not progress_bar)
     with open_file(output_filename, 'w', filters=filters) as merge_file:
         with open_file(file_list[0]) as f1:
@@ -343,8 +346,21 @@ def auto_merge_h5files(
 
         bar.update(1)
         for filename in file_list[1:]:
+
             common_keys = keys.intersection(get_dataset_keys(filename))
+
+            # do not merge specific nodes with equal data in all files
+            common_keys=common_keys.difference(keys_to_copy)
+
             with open_file(filename) as file:
+
+                # check value of Table.nrow for keys copied from the first file
+                for k in keys_to_copy:
+                    first_node = merge_file.root[k]
+                    present_node = file.root[k]
+                    if first_node.nrows != present_node.nrows:
+                        raise ValueError("Length of key {} from file {} different than in file {}".format(k, filename, file_list[0]))
+
                 for k in common_keys:
                     in_node = file.root[k]
                     out_node = merge_file.root[k]
diff --git a/lstchain/scripts/lstchain_merge_hdf5_files.py b/lstchain/scripts/lstchain_merge_hdf5_files.py
index 9c7adfd530..5fad0acba0 100644
--- a/lstchain/scripts/lstchain_merge_hdf5_files.py
+++ b/lstchain/scripts/lstchain_merge_hdf5_files.py
@@ -22,6 +22,22 @@
 
 from lstchain.io import auto_merge_h5files
 from lstchain.io import get_dataset_keys
+from lstchain.io.io import (
+    dl1_params_tel_mon_ped_key,
+    dl1_params_tel_mon_cal_key,
+    dl1_params_tel_mon_flat_key,
+    dl1_mon_tel_CatB_cal_key,
+    dl1_mon_tel_CatB_ped_key,
+    dl1_mon_tel_CatB_flat_key
+)
+
+default_keys_to_copy = [dl1_params_tel_mon_ped_key, 
+                       dl1_params_tel_mon_cal_key,
+                       dl1_params_tel_mon_flat_key,
+                       dl1_mon_tel_CatB_cal_key,
+                       dl1_mon_tel_CatB_ped_key,
+                       dl1_mon_tel_CatB_flat_key
+]
 
 parser = argparse.ArgumentParser(description='Merge HDF5 files')
 
@@ -72,6 +88,11 @@
     help='Skip checks when merging files'
 )
 
+parser.add_argument(
+    '--keys-to-copy',
+    nargs="*", default=[],
+    help='List of duplicated keys to be copied and not to be merged'
+)
 
 def main():
     args = parser.parse_args()
@@ -91,10 +112,13 @@ def main():
     else:
         keys = None
 
+    keys_to_copy = default_keys_to_copy + args.keys_to_copy
+    
     auto_merge_h5files(
         file_list,
         args.output_file,
         nodes_keys=keys,
+        keys_to_copy=keys_to_copy,
         progress_bar=not args.no_progress,
         run_checks=not args.skip_checks
     )