Switched from H4 to H1b, in the meantime got H4 EAD approved

Here is the timeline
Dec 2019 - H1b denied
Feb 2020 - H4 approved based on spouse’s H1b, entered US
Feb 2020 - Filed EAD
Jun 2020 - H1b approved, activated visa via a trip to border
Jul 2020 - H4 EAD approved

Is the H4 EAD even valid now since I’m already on H1b? Is there a way to salvage this coveted EAD ?

You will have to file H1B to H4 COS.