Run multiple instances of Telegram
Telegram offers 2 official versions of their OSX app.

Version 1 is the official maintained version, both available as direct .dmg download on the Telegram website and in the Appstore.

Version 2 is also official, but it's the deprecated objective-c version, also offered as direct .dmg download.  While it's no longer supported, it does still run - and uses separate user credentials.  Newer features are not available, but otherwise it runs fine.