The amplitude of the simulated converted wave waveform in the velocity field of the two-layer porous medium does not match

Hi everyone!
I would like to run the simulations of wave propagation in a model consisting of two homogeneous poroelastic layers.I use the same parameters in Morency and Tromp(2008),however,the simulations of result are different.I checked that the simulated parameters are exactly the same, I don’t know why the results are different ?It is worth mentioning that when I simulate single-layer porous media and poroelastic-acoustic media, the results are consistent with those in the article.
The right figure is my result,and red(left) is Morency and Tromp’s result.After about 0.5s, the waveform will start to be different, that is, after passing through the can i solve this problem?

As always, any advice is greatly appreciated.
Thank you.