So this is a sort of prevention of double spending or loss of coins as a result of sending any of the btc to the wrong node ?
No, it isn't related to "double spending". "Double spending" is an attempt to spend the same coins on the same network twice (usually, but not always, as a means of committing fraud).
It also isn't related to "sending btc to the wrong node"... this doesn't actually make any sense. You don't send btc to a node. You transfer control of BTC from one address to another address (Technially, it is actually transferring control from a private key to another private key, but for the sake of keeping things simple, we'll say "address")...
As BTC and BCC share a common history and (mostly) common technology... without replay protection, it would be simple for a person to take a transaction from BCC network and rebroadcast it on BTC network... or vice versa.
So, theoretically, if one currency isn't worth as much as the other (ie. 1 BTC = 10 BCC) someone could be like... "Hey, I see you have 10 BCC... I'll buy it off your for 5 BTC"... you send them the BCC, thinking you got a good deal (5x!!?! wooooo!
)... they then broadcast this exact same transaction on the
BTC network... and you suddenly find your 10 BTC has been sent to that person!
(Two-way) Replay protection, which is what has been implemented by the BCC devs, makes it so that a BTC transaction is NOT valid on the BCC network... and a BCC transaction is NOT valid on the BTC network. The result being that you don't have to worry about someone being able to take the coins from you unless you specifically create a transaction on that particular network.