Recently I have an idea, and don't know if this could function! I have an Orange Tiny terror and as you know, it only has 3 knobs Volume, tone and gain and could be wonderful if it has 2 channels, so i have the idea to put an extra pair of pots (volume and gain) and a switch, so i can switch between the volume an gain pots and the extra volume and gain, so this could have different settings, one more clean and the other for drive !

Do you think this could function? just passed for my mind
Completely unnecessary. Get a good OD pedal and now you have 2 gain stages (2 channel). Roll off the guitar volume to clean it up, 3 gain stages. Lots of tricks up the TT sleeve.

To mod the amp for 2 channels you would need to add an entire 2nd preamp section with tubes. The TT is a great amp with serious British crunch tone and many experienced guitarists appreciate it's simplicity. If you can't live without 2ch, sell the TT and get a Mesa.
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

Guthrie on tone: https://www.youtube.com/watch?v=zmohdG9lLqY