Here is an excerpt from a recent post by Greg Maxwell. It appears that this is indeed true.
..snip
Through all the history of Bitcoin, altcoin forks copying the code, other reimplementations and many other consensus bugs, some serious and some largely benign, this is the first time someone working on another serious implementation that someone actually uses has actually found one. I might be forgetting something, but I'm certainly not forgetting many. Kudos to awemany. In all other cases they either had the same bugs without knowing it, or accidentally fixed it creating fork risk creating vulnerability without knowing it. It also isn't like there being multiple implementations is new-- for the purpose of this point every one of the 1001 altcoins created by copying the Bitcoin code count as a separate implementation too, or at least the ones which are actively maintained do.
..snip
Thats kinda cool to see actually. how much is a bug bounty worth these days?