LG Innotek supplied the dual-camera setup for the very first dual-camera smartphone back in 2011. Can you guess the name of the handset? It was the LG Optimus 3D. Because the phone took pictures in 3D, the camera needed a second lens to make depth of field adjustments. In the same vein, the HTC Evo 3D also came with a dual camera setup on back. While it has nothing to do with 3D, you might remember the dual-camera setup on the back of the HTC One (M8).
The LG V10 even offered a dual-camera setup for the front-facing selfie camera. The sequel, the LG V20, moved the two lenses from the front to the back where they probably will stay for future variants of the handset.