Why the “which is” can be omitted?

I am writing a scientific paper. And I wrote the sentence as follows:

The nominal prepreg tow height is about 0.15~0.20mm, which is much larger than the Resolution Z-axis (0.011mm). Furthermore, the tow gap nominal width is about 0.1mm~1mm, which is much larger than the Resolution X-axis (0.056mm).

However, my tutor supervisor advised me to remove the second marked "which is". I do not know why. Can anyone explain it to me? Thanks so much.