It's actually worse than pointless, since the addresses used start with a 1 the same as bitcoin. This is something that the creators of the other alternate chains did not mess up! A terracoin address is not easily identifiable as a terracoin address.
+1 I think this was a terrible idea. What happens if we send bitcoin to terracoin addy? Lost coins?
Actually I thought about it and no- the coins are not lost. If you sent Bitcoin to a Terracoin address, then the private key of the owner of the terracoin address you INTENDED to send to, will be the same private key as the Bitcoin address you did send to and vice versa. So basically you may have to ask nice, but the intended recipient on either chain will have the private key for the corresponding address in the other chain. So, no- they aren't lost coins.
And if I remember correctly, since sending from one chain to another is not possible, the coins can be recovered by doing some hacks on the wallet.