Yeah, that was their deliberate plan. Rothbard wrote:

For the first time in my memory, we, 'our side,' had captured a crucial word from the enemy. 'Libertarians' had long been simply a polite word for left-wing anarchists, that is for anti-private property anarchists, either of the communist or syndicalist variety. But now we have taken it over.

He was successful to the point that very few people use it in the old sense anymore, unfortunately. This is especially true in