Davenport-based hyper-prog-metal instrumental shredders Doppelganger have been rolling out tracks from their forthcoming self-titled album since the first single “Plumbus” landed in March of last year. (Yes, we see the Rick & Morty reference here, guys.) The long build-up to the proper album drop on September 25 makes sense in the context of their beyond-detailed omni-metal songwriting, because each four-minute-or-so chunk of this material proves so dense and constantly shifting that it contains its own standalone narrative worth poring over.