My ex fiance says he needs our twins social security numbers to file his taxes on turbo tax even though he is not claiming them. Is this accurate or is he trying to trick

I have my twins 75% of the time. My ex fiance (their father) just asked me for their social security numbers even though I am claiming them both because I have covered most of their expenses since I have them more. He says he needs the SSNs to file on turbo tax. Is this true or is he trying to trick me?