wait until you get the money and then there is a follow up letter coming from the IRS that hopefully will explain what to do about missing money.
just want to check... you both are US citizens (or resident aliens) and both have social security numbers???? those are requirements for the stimulus. (ITIN not permitted)
If you were married in 2018 also, and neither of you said you could be claimed as a dependent by someone else,you should have gotten the $2400. If you did not, it was an error in the IRS system, and only they would know why you didn't. Several people in your situation have reported getting two separate payments, so maybe that will happen for you also.
Only the IRS can tell you, and the only current source for information is the Get my Payment application on their website.
If you do not receive the additional payment by the time that you file your taxes for 2020, you will receive it as a credit on that tax return.
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