Laser double pulses offer interesting opportunities to increase the ablation performance of ultra short laser pulses. In recent published and performed experiments we have presented an optical setup that covers delay times from some picosecond up to 20 ns as well as first experimental results of ablating aluminium and silicon. In this paper we present further results of especially interesting time domains for both materials. The ablation efficiency on silicon with inter pulse delays from 6.3 ns to 15 ns was investigated. In this range the double pulse effect was mainly depending on the fluency. The double pulse efficiency increase is connected with a higher thermal impact on the work piece. The change of delay and repetition rate has no influence on the ablation efficiency for both single and double pulses. The experiments on aluminium concentrated on the pulse delays of 50 ps to 400 ps. The ablation depth per pulse is lower than for single pulse ablation in this range. Double pulse efficiency decreases up to a pulse delay of 150 ps.