Ohh ... I understand the thing with the repeats. Thanks ...
About the post counts, I think it should be standardized (spelling?); if in the forum pages the number of replies are shown, that should also be the case with the Top20. The reason is that most people will think that there is a new post up (someone with 0 replies, as it's normally shown in the forum pages, will have 1 message in the Top20, and he/she might think it's a new reply, which is not the case).
Again, just my 2¢. 😉
Edit: An easy way to solve this (I think) would be just telling the server to show "PostCount = PostCount - 1".