Shubha and Aushubha are auspicious, in our spacious in terms of Vidya Maya and Abhidya Maya. Vidya Maya is that which leads us into Samsara - both are Maya. Just as one is the garland, another one is the snake, but actually the rope is the reality. The same action externally, that's what Krishna says, but internally that third person on the third level is internally offering it to God. Internally, there is no difference externally, and try to keep it as hidden as possible internally.