Unmarried parents living together, can each file a 2441?

[jesusbowls]

Mother had $1250 in Dependent Care FSA employer benefits.  She does not claim the kid as a dependent.  I filed her return listing the kid with code Q, "Not a dependent (but is a qualifying person for the earned income credit and/or the credit for child and dependent care expenses)".  I did this so I could attach Form 2441 to substantiate the Dependent Care amount of $1250 to make it non-taxable.  Her return was accepted.

Today I prepared the father's return.  Claimed child as dependent.  Included form 2441 with $1750 out-of-pocket expenses (being aware of the $3K max per child).  The return rejected citing as follows:

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Error Detail:
Each Form 2441 'QualifyingPersonSSN' provided must not be the same as a Form 2441 'QualifyingPersonSSN' of another accepted tax return for the same tax year. Visit [URL redacted] for additional information. To electronically file with this duplicate condition, an Identity Protection Personal Identification Number (IP PIN) will be required. If you wish to get an IP PIN and you don't already have an account on IRS.gov, then you must register to validate your identity. Please visit [URL Redacted] for further information and resubmit your return with an IP PIN.
Error Resolution:
This return has been rejected by the IRS, because one or more qualifying persons identified on Form 2441 Part II, Line 2(b) has already been claimed as a qualifying person on another taxpayer's return. To identify the qualifying person in question, review the "Description" field above. The path statement has a number enclosed in brackets, [x]. This number identifies the qualifying person on Form 2441 that caused the reject.

Verify that the qualifying person's SSN has been entered correctly. If necessary correct the SSN and resubmit this return.

If no data entry errors are identified, and you want to electronically file this return with the information currently entered on Form 2441, an Identity Protection PIN will be required. Visit [URL redacted] for further information.

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So, I'm confused by the error resolution.  If the father obtains an IP PIN for the child, can we legitimately file the father's return as-is with the 2441, or is it improper to file a 2441 for the same kid on two different returns?

Thanks!

[TaxGuyBill]

It is improper to claim the credit on Form 2441 on both return.

Because the parents are living together, only one parent can claim ALL benefits for the child.  The other parent can't claim any benefits for the child.