### Discussed in https://github.com/apache/airflow/discussions/19366

<div type='discussions-op-text'>

<sup>Originally posted by **a-pertsev** November  2, 2021</sup>
### Apache Airflow version

2.2.1 (latest released)

### Operating System

Ubuntu 20.04 LTS

### Versions of Apache Airflow Providers

apache-airflow-providers-amazon==2.3.0
apache-airflow-providers-apache-cassandra==2.1.0
apache-airflow-providers-ftp==2.0.1
apache-airflow-providers-google==6.0.0
apache-airflow-providers-http==2.0.1
apache-airflow-providers-imap==2.0.1
apache-airflow-providers-jdbc==2.0.1
apache-airflow-providers-mysql==2.1.1
apache-airflow-providers-postgres==2.3.0
apache-airflow-providers-presto==2.0.1
apache-airflow-providers-slack==4.1.0
apache-airflow-providers-sqlite==2.0.1

### Deployment

Virtualenv installation

### Deployment details

_No response_

### What happened

Got error when manually run newly created task in already finished dag run (in UI).

### What you expected to happen

"Run" button should work without exceptions.

### How to reproduce

1. Define a dag with some tasks.
2. Create dag run (manually or by schedule)
3. Add new task into dag, deploy code
4. Select new task in UI and press "Run" button

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)
</div>
airflow/www/views.py
"""Duplicate Multiple connections"""
        for selected_conn in connections:
            new_conn_id = selected_conn.conn_id
            match = re.search(r"_copy(\d+)$", selected_conn.conn_id)
            base_conn_id = selected_conn.conn_id
            if match:
                base_conn_id = base_conn_id.split('_copy')[0]
            potential_connection_ids = [f"{base_conn_id}_copy{i}" for i in range(1, 11)]
            query = session.query(Connection.conn_id).filter(Connection.conn_id.in_(potential_connection_ids))
            found_conn_id_set = {conn_id for conn_id, in query}
            possible_conn_id_iter = (
                connection_id
                for connection_id in potential_connection_ids
                if connection_id not in found_conn_id_set
            )
            try:
                new_conn_id = next(possible_conn_id_iter)
            except StopIteration:
                flash(