Step 1 :Let's denote the amount of money invested in AAA, A, and B bonds as x, y, and z respectively.
Step 2 :We have three equations based on the problem: \(x + y + z = 26000\) (total investment), \(0.05x + 0.07y + 0.12z = 1880\) (total return), and \(x = 2z\) (the client wants to invest twice as much in AAA bonds as in B bonds).
Step 3 :Solving this system of equations, we find that \(x = 12000\), \(y = 8000\), and \(z = 6000\).
Step 4 :Final Answer: The client should invest \(\boxed{\$ 12,000}\) in AAA bonds, \(\boxed{\$ 8,000}\) in A bonds, and \(\boxed{\$ 6,000}\) in B bonds.