Relay bitcoin transaction attack A user sending coins broadcast transaction hash to bitcoin network. Now if someone is able to copy the message (hashed transaction) and relay it multiple times it could lead to possible disruption. 

Eg:

Node 1 sends a transaction to node 2. Node 2 forwards to node 3 and so on. This transaction gets mined.

Now what will happen if node 2 will try to relay the same message again?

How this is prevented in bitcoin network?
Now what will happen if node 2 will try to relay the same message again?
How this is prevented in bitcoin network?

The transaction is the same as one that the nodes have already seen; it has the same txid, so they will ignore it.
Bitcoin does not use an accounts based system. Rather Bitcoin uses a transaction outputs model, so each input directly references a transaction output that is being spent. So there is no problem with transactions being replayed; they have already been seen so they're just duplicates that can be ignored.