why receiving 2 letters when using telnet?

Question

I am looking this page:http://netty.io/wiki/user-guide-for-4.x.html

when I use 'telnet 127.0.0.1 8080' and send some letters:

why..?

Answer 1

Because it first "prints" what you entered there and then also what is echoed back.

This should give you a better idea:

echo "test" | nc 127.0.0.1 8080