No, you can't split DRE like that. It counts as 2 fire, 2 water, 2 fighting, 2 everything while in play, although you only get to utilize the effect of two of any of those energy at a time, so Flare Blitz's stipulation that you discard all fire energy attached to Infernape means you get rid of all energy attached to it that count as fire energy (like regular rainbow, or multi, or Holon's Castform), even if you weren't using those energy to satisfy a specific energy requirement. DRE always counts as every type of energy while in play, including fire, so the entire card gets ditched by Flare Blitz no matter how you look at it.