The seller sold the same property to two different people and cheated.

First owner got the property in 2004
I bought it on 2010, and i transferred the property to other family member, 2014.

Yesterday the first owner told me that he is the sole owner. however upon checking the document
of the two, there are some difference.

1) First owner has 4 previous reference document number (PR Number)
2) In my document has only 1 previous reference document number out of the above four (PR Number)
I knew in 2011 Land grabbing law was introduced
Please help me how to take legal action,