No, that's how it works.
It's a lot of work to correctly remove posts, which is why the toolkit just replaces them with the word "Deleted".
If you've now installed some anti=SPAM MOD (like the RAC MOD), then you won't get any more.
phpBB3 has much more powerful features built in to stop spammers and delete all their posts. You should be thinking about converting to phpBB3 now. Support for phpBB2 ends in a few weeks.