Technically speaking since your name is not there in the sale deed therefore you can't take the benefit of loan paid on first home, because to show it under income from house property of son he needs to be the owner or atleast one of the owner of the house since he is not he cannot claim benefit of section 24 in case of first house.
However if your parents gift you such property then in that case you can claim deduction under section 24 for such house.
In case if you claim such house is owned by you there is a risk of getting a notice to show the sale deed, so my advice would be to not show it and create some income of parents and let them pay it.
If you still want to show one as self occupied and one as deemed let out then obviously showing 1st home as self occupied would be more beneficial because if you show 1st house as self occupied your net loss from house property would be 1.27 lacs and if you show second as self occupied your net loss from house property would be 15000 so it's better to show house 1 as self occupied.
From the above question I am assuming the son is doing a job so he can't transfer any money to parents however if he is doing some business let the parents themselves pay the loan and claim benefit of such repayment.
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