Foster Son - Claimed by more then one family

HI There,

 

I am a first-time foster parent. I claimed my foster son on my taxes this year as directed by the agency that I have my license through. I recently learned that his biological family (kinship placement) also claimed him on their taxes last year as well. Are we both able to claim that deduction or do I need to amend my return? 

 

Thanks so much for the guidance!