It all depends upon tge agreement between you and the builder. Normally if the building is constructed you will get 2 flats unless you have agreed to or he has made a design to club it as a single flat.

Generally what happens is that the developer takes the land and an agreement is made and registered between the developer and the owner as to the specifications/details as to how to proceed how it is to be built and what portion would the owner of the property receive.

You will get 2 separate flats  on redevelopment 

Agreement for redevelopment signed by you with builder would mention the flats you are entitled to on redevelopment 

You will definitely get 2 flats or 1 flat with area consisting 2 flats. 

Dear Client,

You have to explain in very detail as one cannot answer when information is not gathered.

Thank you

If you are owner of two flats then the developer has to consider allotting you two different flats on the basis of two flats acquired from you in the redevelopment process, he cannot club both together and merge  the same to his convenient, it is an illegal and unlawful act.

The developer has to enter into an agreement with the owners of the flat on ther terms that are mutually agreed by both parties. 

- Legally you are entitled to get two flats , as there is two separate agreement , hence you can enter into an agreement with the builder for getting two flats. 

2 flats will have to be allotted

the builder cannot club into one

if the sanctioned building plans show 2 flats then 2 new flats will have to be allotted 

it is of no significance that both the flats are owned by the same person