Even this was what both Karna and Duryodhana had decided to be the means for bringing about the death of Arjuna; and for this they had planned the double encounter.
सा हि दुर्योधनस्यासीन्मतिः कर्णस्य चोभयोः। अर्जुनस्य वधोपाये तेन द्वैधमकल्पयत्॥