diff --git a/lib/filter_nb.c b/lib/filter_nb.c
index bb34efd34c..50325a39f9 100644
--- a/lib/filter_nb.c
+++ b/lib/filter_nb.c
@@ -429,6 +429,45 @@ bool plist_is_dup(const struct lyd_node *dnode, struct plist_dup_args *pda)
 	return pda->pda_found;
 }
 
+static bool plist_is_dup_nb(const struct lyd_node *dnode)
+{
+	const struct lyd_node *entry_dnode =
+		yang_dnode_get_parent(dnode, "entry");
+	struct plist_dup_args pda = {};
+	int idx = 0, arg_idx = 0;
+	static const char *entries[] = {
+		"./ipv4-prefix",
+		"./ipv4-prefix-length-greater-or-equal",
+		"./ipv4-prefix-length-lesser-or-equal",
+		"./ipv6-prefix",
+		"./ipv6-prefix-length-greater-or-equal",
+		"./ipv6-prefix-length-lesser-or-equal",
+		"./any",
+		NULL
+	};
+
+	/* Initialize. */
+	pda.pda_type = yang_dnode_get_string(entry_dnode, "../type");
+	pda.pda_name = yang_dnode_get_string(entry_dnode, "../name");
+	pda.pda_entry_dnode = entry_dnode;
+
+	/* Load all values/XPaths. */
+	while (entries[idx] != NULL) {
+		if (!yang_dnode_exists(entry_dnode, entries[idx])) {
+			idx++;
+			continue;
+		}
+
+		pda.pda_xpath[arg_idx] = entries[idx];
+		pda.pda_value[arg_idx] =
+			yang_dnode_get_string(entry_dnode, entries[idx]);
+		arg_idx++;
+		idx++;
+	}
+
+	return plist_is_dup(entry_dnode, &pda);
+}
+
 /*
  * XPath: /frr-filter:lib/access-list
  */
@@ -1291,6 +1330,13 @@ lib_prefix_list_entry_ipv4_prefix_modify(struct nb_cb_modify_args *args)
 		const struct lyd_node *plist_dnode =
 			yang_dnode_get_parent(args->dnode, "prefix-list");
 
+		if (plist_is_dup_nb(args->dnode)) {
+			snprintf(args->errmsg, args->errmsg_len,
+				 "duplicated prefix list value: %s",
+				 yang_dnode_get_string(args->dnode, NULL));
+			return NB_ERR_VALIDATION;
+		}
+
 		return prefix_list_nb_validate_v4_af_type(
 			plist_dnode, args->errmsg, args->errmsg_len);
 	}
@@ -1319,6 +1365,13 @@ lib_prefix_list_entry_ipv6_prefix_modify(struct nb_cb_modify_args *args)
 		const struct lyd_node *plist_dnode =
 			yang_dnode_get_parent(args->dnode, "prefix-list");
 
+		if (plist_is_dup_nb(args->dnode)) {
+			snprintf(args->errmsg, args->errmsg_len,
+				 "duplicated prefix list value: %s",
+				 yang_dnode_get_string(args->dnode, NULL));
+			return NB_ERR_VALIDATION;
+		}
+
 		return prefix_list_nb_validate_v6_af_type(
 			plist_dnode, args->errmsg, args->errmsg_len);
 	}
@@ -1350,6 +1403,13 @@ static int lib_prefix_list_entry_ipv4_prefix_length_greater_or_equal_modify(
 		const struct lyd_node *plist_dnode =
 			yang_dnode_get_parent(args->dnode, "prefix-list");
 
+		if (plist_is_dup_nb(args->dnode)) {
+			snprintf(args->errmsg, args->errmsg_len,
+				 "duplicated prefix list value: %s",
+				 yang_dnode_get_string(args->dnode, NULL));
+			return NB_ERR_VALIDATION;
+		}
+
 		return prefix_list_nb_validate_v4_af_type(
 			plist_dnode, args->errmsg, args->errmsg_len);
 	}
@@ -1387,6 +1447,13 @@ static int lib_prefix_list_entry_ipv4_prefix_length_lesser_or_equal_modify(
 		const struct lyd_node *plist_dnode =
 			yang_dnode_get_parent(args->dnode, "prefix-list");
 
+		if (plist_is_dup_nb(args->dnode)) {
+			snprintf(args->errmsg, args->errmsg_len,
+				 "duplicated prefix list value: %s",
+				 yang_dnode_get_string(args->dnode, NULL));
+			return NB_ERR_VALIDATION;
+		}
+
 		return prefix_list_nb_validate_v4_af_type(
 			plist_dnode, args->errmsg, args->errmsg_len);
 	}
@@ -1424,6 +1491,13 @@ static int lib_prefix_list_entry_ipv6_prefix_length_greater_or_equal_modify(
 		const struct lyd_node *plist_dnode =
 			yang_dnode_get_parent(args->dnode, "prefix-list");
 
+		if (plist_is_dup_nb(args->dnode)) {
+			snprintf(args->errmsg, args->errmsg_len,
+				 "duplicated prefix list value: %s",
+				 yang_dnode_get_string(args->dnode, NULL));
+			return NB_ERR_VALIDATION;
+		}
+
 		return prefix_list_nb_validate_v6_af_type(
 			plist_dnode, args->errmsg, args->errmsg_len);
 	}
@@ -1461,6 +1535,13 @@ static int lib_prefix_list_entry_ipv6_prefix_length_lesser_or_equal_modify(
 		const struct lyd_node *plist_dnode =
 			yang_dnode_get_parent(args->dnode, "prefix-list");
 
+		if (plist_is_dup_nb(args->dnode)) {
+			snprintf(args->errmsg, args->errmsg_len,
+				 "duplicated prefix list value: %s",
+				 yang_dnode_get_string(args->dnode, NULL));
+			return NB_ERR_VALIDATION;
+		}
+
 		return prefix_list_nb_validate_v6_af_type(
 			plist_dnode, args->errmsg, args->errmsg_len);
 	}
@@ -1492,6 +1573,17 @@ static int lib_prefix_list_entry_any_create(struct nb_cb_create_args *args)
 	struct prefix_list_entry *ple;
 	int type;
 
+	if (args->event == NB_EV_VALIDATE) {
+		if (plist_is_dup_nb(args->dnode)) {
+			snprintf(args->errmsg, args->errmsg_len,
+				 "duplicated prefix list value: %s",
+				 yang_dnode_get_string(args->dnode, NULL));
+			return NB_ERR_VALIDATION;
+		}
+
+		return NB_OK;
+	}
+
 	if (args->event != NB_EV_APPLY)
 		return NB_OK;