Yes, it's not "glue" it's "solvent" - and you are not gluing PVC together, you are actually *welding* them together. Yes, there's a difference :-) glue is adhesive (e.g. sticks stuff together without penetrating the stuff). PVC cement is actually "melting" the pvc during the join/weld. So it's important to use glue on both pieces, so that the solvent has several seconds to start melting the PVC so that when you push them together both sides are squishy and slightly melted.