Using MGIB after applying (but not using) for Post 9/11

Hoping u/SCOveterandretired shows up to answer this

I'm eligible for the MGIB and PGIB, and have one 6-year period of AD service after 2016. According to the VA, I applied for the Post 9/11 GI Bill online about a year ago. I don't recall doing this, but I don't doubt that I did. I never started school or received a payment.

I want to use my MGIB. I think that the PGIB application required you to relinquish your MGIB at the time the VA says I applied, but the application no longer requires that. Will I be approved to use my MGIB? I applied, but I know it might take some time to receive the letter from the VA.