No quite, because it also does the same even if the base version is the latest. In that case it just launches itself again. You need to set the environment variable AUTOUPDATER_DUPLICATI_SKIP_UPDATE=1 to disable the auto-update system.
A bit off topic, but no they do not chain.
The reason for this setup is that the main process stays alive. Then after an update is applied, the spawned process quits with a special signal that causes the main process to start the latest (aka the updated) version. This allows the process to “re-start” without actually restarting the parent process.
We tried to use an in-process updater system previously (based on isolation with app-domains) but a number of users reported that it did not work cleanly in their setups. You can revert to this by setting the environment variable AUTOUPDATER_USE_APPDOMAIN=1.