H1 applied 2 times & USCIS asking explanation

I am on H4 and applied for H1B on April 30th & i didn’t receive my receipt number until may 30. So my employer sent application again with same details. Now got 2 receipt numbers. Now got RFE asking explanation why you applied for the same individual 2 times. What explanation we can give for this & what are the chances of approval. Can anyone please answer this?

You can say the delay in recieving the acknowledge from USCIS. So resent.