Filing H-4 EAD again if other H-4 EAD application is pending

USA H4 Visa
1

Hi,
I wanted some help urgently for H-4 EAD application.
My wife’s H-4 EAD is due to expire in July 1st week. I have a I-797 approved till OCT 2021 and my wife’s H-4 stamp is approved till OCT 2021 as well.

I wanted to know if this is possible

  1. Can I file stand alone H-4 EAD extension using my present I-797A
  2. If my new employer files for H-1B transfer in premium processing using concurrent filing for H-1+H-4, can I also file for H-4 EAD here again to get the benefit of 3 years validity?

Please let me know if the above is possible. Also, what happens is USCIS sees two H-4 EAD applications… does it void the 1st one and only approve the 2nd one?

Thank you!!