diff --git a/cylc/flow/parsec/util.py b/cylc/flow/parsec/util.py
index 785612639a..2bc2aeb36e 100644
--- a/cylc/flow/parsec/util.py
+++ b/cylc/flow/parsec/util.py
@@ -212,7 +212,7 @@ def replicate(target, source):
                 target[key].defaults_ = pdeepcopy(val.defaults_)
             replicate(target[key], val)
         elif isinstance(val, list):
-            target[key] = val[:]
+            target[key] = type(val)(val)
         else:
             target[key] = val
 
@@ -247,7 +247,7 @@ def poverride(target, sparse, prepend=False):
                 # Override in-place in the target ordered dict.
                 setitem = target.__setitem__
             if isinstance(val, list):
-                setitem(key, val[:])
+                setitem(key, type(val)(val))
             else:
                 setitem(key, val)
 
@@ -302,13 +302,9 @@ def m_override(target, sparse):
                             "parsec dict override: no __MANY__ placeholder" +
                             "%s" % (keylist + [key])
                         )
-                    if isinstance(val, list):
-                        dest[key] = val[:]
-                    else:
-                        dest[key] = val
 
                 if isinstance(val, list):
-                    dest[key] = val[:]
+                    dest[key] = type(val)(val)
                 else:
                     dest[key] = val
     for dest_dict, defaults in defaults_list: