I noticed today that the cck block display settings are overriding the basic display settings. For instance I have field_1, on the basic display settings I have it set to hidden so that it does not render in $content. But I have the display setting in the cck_blocks display settings as default. What I end up with is field_1 displaying in $content and in the cck block that I have added. I'll see what I can dig up to help resolve this.