The pair-precision technique, used to reduce round-off errors, was applied to the 6th-order symplectic integration method for integrating the equation of motion of the two-body problem. Analytical comparisons confirm that the implementation of pair-precision arithmetic operation functions reduces integration errors by a factor of 108 and a precision gain of around 20 digits along the orbit is obtained. Manipulated integration comes at the cost of approximately a 3.9-fold increase in CPU time, however, it is 2.1 times more efficient than using quadruple-precision computation. Integration with the pair-precision technique can be used for checking the validity and setting time limits for similar numerical calculations. More accurate calculations can extend the usefulness of predictions for evolutionary studies in the dynamics of the Solar System.