Find the value of \(a\) such that the following two matrices have the same determinant.

\[\left[\begin{array}{ccc}1 & 3 & 0 \\-2 & a & 0 \\0 & 0 & 4\end{array}\right],\left[\begin{array}{ccc}4 & 0 & 0 \\0 & -3 & 2 a \\0 & \frac{1}{2} & -1\end{array}\right]\]