Checking turntable output

I just put in a new desktop computer and I am trying out my Pyle turntable with it. The left and right channel are visually identical (waveform) in every record I have tried. How can I be sure that my turntable is returning stereo sound instead of two mono tracks?

Use a record that you know has a strong stereo spread, then listen through headphones.
Mono will sound like it is playing in the middle of your head,

The “scientific” way to test if both channels are absolutely identical:
Apply the “Vocal Remover” effect to the recording. 2 identical channels will produce silence.