here is the confusion - and I see this a lot on these boards -
yes, you received a letter stating you received $1400, but there were TWO letters - one sent to each spouse and each one stating receipt of $1400.... in turbo tax when asked how much you received, you were to respond $2800 - because that is the SUM of the two letters.
the stimulus was $1400 PER PERSON - not per HOUSEHOLD
go back to your bank statements from March - May, 2021 - I suspect you will see the $2800 deposit.