ChanSpy tips "same exten"

Hello !
I’m trying to understand how chanspy work. But as i test it, i got some problems.

Chanspy cant spy a confbridge. But only extensions.
Unfortunately i got this situation :

User 1 , User 2, User 3

User 1 and User 2 are connected on the same extension “111”

User 3 is connected on the “222” extension

User1 is in a call with a random smartphone
and User2 is in a call with an other random smartphone
How can User3 chanspy User1 and not User 2 ?

Thanks by advance.

Chanspy your endpoint 111 that user 1 and user 2 are registered to.

If you don’t get the channel you want press * and have chanspy hop to the other channel.

https://wiki.asterisk.org/wiki/display/AST/Asterisk+13+Application_ChanSpy

Otherwise have User 1 and User 2 register as different endpoints.