To add another character to the game (same player but another sprite):
Game scene → Character → player object → right click → duplicate → duple click on the new duplicated object → change the sprite animations to the new one (Idle and Move animations) → Game scene events → you need to create new events for the new added character in the client codes and in the server codes.
I programmed the template for 1 character, to add more, you need to adjust the events to control other characters.