As I was reading Bitcoin hashing algorithm, I see that a Block Header contains hashes in the form of fields like
hashMerkleRoot . I have following questions:
1) Are the transactions 100% secure? If yes, then I am wondering if Hash is the reason behind it? Since moving forward in a hash is easy than backwards.
2) Suppose there are two identical transactions happening at the same time, are those transactions are going to get differentiated based on the Hashes ?