Please contact the concerned authority on the contact numbers or email address provided in the contact us.

1. No need to collect duplicate remittance challan reciepts if property mutation is already been transferred on your name. 

2. Still if you want to be safe you can ask seller to provide you original reciepts or apply for duplicate.

Yes you can apply for the duplicate or seek certified copy

Collect the original challans 

it is proof that money has been paid to BDA 

1. you can obtain the certified copy of the challan from the BDA

2. or, obtain the account statement of the relevant plot, if the payment is reflecting, no need for the certified copy,

3. 

1. It's preferable to have the original remittance challan payments the allottee would be possessing. However, the original challan obtained after payment to the BDA alone, does not confer title to the property.

2. It's not absolute necessity at the time of selling the property.

3. There is no need to get a duplicate copy of the remittance challan and the photocopies would suffice.

4.  Try to contact the original allottee and impress upon him to handover the originals to you. You can take the help of middleman in this regard.

1. Ask for original challan from the original owner if he has no record of same you can obtain certified copy of same from the authority though since you have photocopy you don't need to worry in same.

If the sale deed in your name is already registered the it reflects the fact that yo have completed the payments.

In other words after the registration of sale deed keeping the proof of payment of full consideration money is no more required.

So forget the remittance receipts. 

You can apply for a office certified copy of the same in case anyone wants it for various reasons.

1. File RTI application by annexing the photocopy and request for "certified copy" of the challan.

2. The above would be legally sufficient for the required sale purposes.

Remittance challan payments receipts are must rerecords to prove payment deposited in cash or cheque into their bank account

At least have the copies.

You can always get a certified copy of the challan held by the BDA by applying for it following the procedures, however it may be noted that this will form part of the document with respect to your property especially at the time of selling it.