[LAU] How do you make a sound in both speakers at once, but not stereo

Hey folks, I'm not an audio engineer and i don't even play one on TV. I am a music lover/audiophile who wants to learn about engineering so bear with me here. I understand that when you hear something in the center of your sound stage it's because the sound is equally loud in both channels and in phase. If you hear it spread evenly across the sound stage or even "everywhere in front of you" the sound is equal in both channels and out of phase. I heard a recording the other day where a singer was equally loud in both channels, but she was not center stage. Instead there was one of her in each channel. How is that done? Thank you. Bearcat M. Sandor