Question is not about legality of CPT, rather it is about abuse. There are two parts: -

First part - Schools issuing CPT

I agree school will issue CPT, however while doing that school don't ask about your previous CPT or OPT or anything like that. They just issue CPT because they are allowed to.

Second part -

Now, USCIS will see this as an abuse of CPT. Someone who already utilized their OPT period after completing their masters (I don't know much about folks who completed their undergrad and doing masters) and working using CPT from another masters . How do you explain that to USCIS ?

I wished some one had told me about this CPT crap. Again, I am just sharing info that I know and that's all. Not trying to scare any one but trust me, this CPT crap will come back to bite you.