Deduction under section 24

no emi should be paid by second holder 

then only he can claim the deduction 

only the payer is eligible to get the benefits

is it written in section that only payer is eligible ?

the deduction of interest on home loan is allowed on the basis of home loan certificate issued by the lender. since 1st co owner is the borrower of loan the lender will issue the certificate only to 1st co owner. please refer proviso to sec 24

The bank has issued certificate in the name of both co-borrowers and proviso does not talk about co-borrowers repayment.

Provided also that no deduction shall be made under the second proviso unless the assessee furnishes a certificate, from the person to whom any interest is payable on the capital borrowed, specifying the amount of interest payable by the assessee for the purpose of such acquisition or construction of the property, or, conversion of the whole or any part of the capital borrowed which remains to be repaid as a new loan.

Please clarify if you did not repaid the loan then how can you say that you have taken a loan. You are only for namesake co-owner and co-borrower.
If you indeed wish to claim deduction for the interest which was paid by 1st coowner you and the 1st coowner has to make an agreement whereby 1st coowner will undertake to repay the EMI on your behalf and the repayment shall be deemed to be made by him on your behalf only. Then only you can claim the benefit.
Remember it's a jointly owned property. Ideally you are liable for 50%of all the benefits and also oblige to discharge only 50%of all the liabilities associated with the property. What you are now trying to take the benefit of other Co owners share. You also want to take the benefits of your share despite the liability is undertaken by other person.
Under the income tax act many provisions operates on substance basis rather than in legal form. This is one of them. The law will not allow to take the entire benefits by you unless adequate safeguards are made.
In your case the 1st owner can claim the full interest by substantiating the same as the entire interest was paid by him out of his sources of Income.
So you will not be blanketly allowed the full benefit without the undertaking from the payer that he had paid the EMI on your behalf and that he did not take any benefit under the income tax law.
Then only you will be eligible, else you may be denied.
Hope this helps.