The moment you become aware of the ego in you, it is strictly speaking no longer the ego, but just an old, conditioned mind-pattern. Ego implies unawareness. Awareness and ego cannot coexist.
Hmm ... I don't know if awareness and ego can coexist, a la parallel computer processing. But I do know, from experience and observation, that mind can rapidly shift between awareness and ego, a la sequential computer processing (time sharing). And I think that's the default state of mind: to be aware of something (sensory input, for example), then think about it from an ego perspective (interpret it through the filter of self), be aware, think, be aware, think, etc. Since this shifting between awareness and ego-based thought occurs so quickly and continuously, the result IS a kind of (faux) coexistence of awareness and ego, just like time sharing on a computer comes off like parallel processing.
The only exception to this would be extended periods of pure awareness or pure ego ... as in self-less meditation or a ME! tantrum. Other than that, awareness and ego are always hanging around together.
Merrily, merrily, merrily, merrily ...