Steinberg 242 the sound from the headphones is duplicated into the microphone


I`m streamer on Youtube. I connect the microphone to the mixer, and the mixer to the sound card via the line input (the microphone is quiet, so I preamp). I turn on the function LOOPBACK. The sound from the microphone is good. But the sound from the PC (sound from the game) is duplicated to the microphone - the sound is twofold. How do I fix the situation? Thank!

You mean its an “echoe” or something?