double bottom as in postufgram #59

Hidden accounts are not displayed in the general list of accounts, they can only be accessed by entering a passcode in the Telegram client blocking mode. The number of hidden accounts "Double bottom" is not limited.

I can’t explain what it is and why it is needed better than here:
https://telegra.ph/Kak-my-vnedrili-skrytie-akkauntov-v-Telegram-ili-DurovDobavDvojnoeDno-08-29-2