Who will be the actual Owner?

Hello Sir/Madam We belong to Telangana. We bought an agricultural land in the year 2016 AUG from an ST to whom(to his ancestors, he got it from his grandpa) the land was given as Inam in 1955. Before buying the land.we have gone through all possible documents. 1.we knew that They have no right to sell the Inam Land until they hold land for at least 12 years.It is clear that the land is under his hold till 2016.so he has the right to sell the land to us.so we took a step forward to buy. 2.checked the EC, Pahani, 1B. 3.took out all the link documents and every possible document required from the local office and showed them to a known high court lawyer. 4.he said everything is perfect you can go forward. 5.at that time the land was under the mortgage( on the name of the person who sold us) in ICICI bank till 2016.we paid his loan amount and cleared everything. 6.so we bought it with video and audio evidence thinking they help us in future if any problem occurs.all telephone coversations are recorded and we shot video at registrar office. 7.we bought that with the amount we got from a personal loan.we are paying 20k per month from our salaries. Now the Problem is Telangana state govt is re-surveying all the lands.to avoid future legal issues.all the local govt websites are being reformed.and that's a good sign. But recently we came to know that the person who sold the land to us had already sold that land to another person in 2009. But the person who bought the land didn't do mutation till now(2018).so we didn't find his name in any of the govt documents we verified earlier. so we thought all the docts were clear and we bought the land. Now all the documents like EC, Pahani, 1B are in My Name. did mutation within 45 days. started doing farming on that land immediately.growing vegetables since 2016 till now. have a 3 phase electricity connection paying current bills. constructed a permanent structure constructed in the land and barbed wire fencing. we are being regularly there. we spent 10 laks to level up the land,fencing,pendals,electricity ans misc. the land was mortgaged in PNB bank for 6 lakhs. till now nobody has turned out there claiming that it is our land.the person who bought it in the middle(before us) doesn't even know whats happening here. recently the person who belongs to the same Thanda(clan- cousin of the seller) told us it's a double registration.because he was in family issues with his brother and spoke out the truth to us. dear sir/madam now please tell us.what we have to do if that person claims as his land in future.we struggled like anything to bring that land to a proper shape.we are planning to sell another land in the village and pay the personal loan amount to get rid of the EMIS(that we can't pay) we are still struggling to pay the loan amount. we followed we followed everything legally. can You please tell us who would be the actual owner(according to law).Thanks In Advance.