Zombies in RE5?

If the enemies on the conveyor belt are starving, discarded test subjects and not zombies, why do they seem to have some decomposition and use the exact same moans/noises the zombies in the Resident Evil remake make? Not merely similar, but the same audio. Surely it wouldn't be too hard for Capcom not to recycle zombie moans for a different enemy? I wouldn't be surprised if it's a hint from Capcom that the conveyor belt enemies (and from Lost In Nightmares) ARE indeed zombies. Albeit weak and possibly from a different viral strain (Progenitor?). Anyone care to share your thoughts or explain?