If you are editing *.2da file via patcher you SHOULD NOT MENTION IT IN [install_folder] section at all.
Also, in 'tslpatchdata' folder you should put ORIGINAL, not modified 2da's. If you put your modified file it may cause problems for people, who don't already have that 2da in their override.
TSLPather works this way: it looks for required 2da in Override. If file found - it applies changes you listed in 2da section. If not - it copies file from tslpatchdata folder to the override, then applies changes to it. So, if you put modified file to tslpatchdata you may get duplicate entries in them or some other bad things (if your file is made with lots of mods).
After all 2da/gff/other things are patched, patcher will copy files listed in [install_folder] section.