Agpa impact on sale deed

Hi All,

  I bought a flat in a residential apartment. Flat fell under land-owners' share as per agreement signed between land owner and builder in 2006.

  Land-owner and builder had another AGPA signed in 2011 for my flat specifically. My sale deed was executed via builder's signature stating this AGPA document number.

Do i need to keep original copy of this AGPA document signed between builder and land-owner for my flat. Is sale deed not valid without this agpa document's original copy?

Thanks