How can I use multiple accounts with Telegram?

Update of June 2020

Telegram destop now supports multiple account out of the box:

https://telegram.org/blog/profile-videos-people-nearby-and-more#multiple-accounts-on-telegram-desktop

Old Update

For macOS, use the official telegram for macOS: https://macos.telegram.org/ . It supports multiple accounts out of the box.

Old solution

With telegram desktop installed:

mkdir ~/.telegram2ndprofile 
telegram -many -workdir ~/.telegram2ndprofile 

Source

You can use Franz.

Franz allows you to add each service many times. This makes Franz the perfect tool to manage multiple business and private accounts at the same time. You could even use five different Facebook Messenger accounts at once, if some inexplicable reason urges you to do so.

What I do is run the Telegram binary as a different user

cd ~/Downloads/Telegram/
sudo -u otheruser ./Telegram