if your EAD is not approved yet, NO you cannot work legally.

If you were re-registering for EAD that would have been a different scenario, you could work, but without prior EAD i do not think you can legally work.
@NepaliSaila is absolutely right.

Initial Application approved on March 3, 2017. ( Filled in 2015 ).

Second application is closed ( March 3, 2017) saying "the applicant has another benefit through other means".

It is not true. Even though I have an another application pending, I am not approved and I do not have any other active benefit/s besides pending application.

I am waiting for the NOTICE to arrive, but just curious if anyone been through this.

Anyone had to file motion to reopen ? If yes, which form to file MOTION TO REOPEN I-821 ??