Consider two circles defined by the equations \( x^2 + y^2 - 6x + 8y - 11 = 0 \) and \( x^2 + y^2 + 4x - 2y - 8 = 0 \). Determine the coordinates of the points of intersection and find the sum of the coordinates of all the points of intersection of these two circles. Let's think step by step and output the final answer within \boxed{}.
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