We present a few possibilities for forming an extended energy spectrum and producing a varied slope in different double-shock models. In our previous work, the converging double-shock model would provide more kinetic energy injecting into the particles acceleration. The high efficient injection rate excited by amplified magnetic turbulence in the converged region made the extended energy spectrum be possible. In our present work, the pileup-shock model provides an opportunity of the re-accelerated processes of the particles on the merged precursor region. With the expending of the precursor region, more and more particles can be participated into the pileup-shock system, the ``ankle'' slope of the energy spectrum would be produced due to the enhancement magnetic turbulence between the merged pileup-shock. We have proved that the converging double-shock model taken a negative effect on the accelerated particles and produce an energy ``break'' slope. At present, we also investigate that a positive effect on particle acceleration in pileup twin-shock scenario can produce an ``ankle'' slope on the energy spectrum.