Having legacy and unified alerting at the same time

Hi, I’d like to know if it’s possible to have both legacy and unified alerting active at the same time on OSS Grafana.

The official documentation on the Upgrade to Grafana page mentions that it can be done:

Existing OSS installations with legacy dashboard alerting will have two alerting icons in the left navigation panel - the old alerting icon (marked as legacy) and the new Grafana Alerting icon.

However, I can’t find any way to achieve this.