One side of double sink backing up

In the pic there is silver piping running to the disposer on the left side sink. The white piping runs up to a sink that has a dish dryer in it. When I run water down the left hand sink the right hand sink piping will back up and gurgle. I removed the white piping down to the elbow that fits into the main line and ran a 20′ auger down it. Still, when I run water in the left sink, the right one backs up. Any ideas on what might be going on?
Thanks!
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