H4 => H1B => H4 EAD

[hmaster]

I used to be on H1B before, but my last entry was H4. As soon as I entered, I applied for H4 EAD. Meanwhile my employer wanted me to start earlier (couldn't wait for 90 days for EAD to arrive), so I applied for COS to H1. 

 

My H1 was approved under PP in 15 days. Exactly after 20 days or so, my H4 EAD was approved and dispatched in mail. 

 

As my current status is H1, I understand that the H4 EAD doesn't matter.

 

But my question really is: - 

 

In future if I exit the country and re-enter using my h4 visa under H4 status, can I use the same approved EAD (under H4 status) to work; or do I need to re apply for EAD again?  I see no point in re-applying as how can USCIS re-issue the exact same EAD again when its already active in their system as approved. 

 

JoeF or other experts please assist...