You can omly have a single texture path. There's no such
thing as two of them. It's defined in "File"->"Options..". The
names of your textures are appended to the value of
"Texture name prefix" thus forming the full path to your textures.
If you want to see the texture path of a .p3d, i
recommend you open it up with a hex editor.
If all your textures came with the game, your prefix should
read "data\" (the textures will be opened from "Data.pbo").
If you have your own textures, the prefix should point to
your addon. The same thing if you're using both custom and
original game textures, omly in this case, you need to copy
the textures you use from "Data.pbo" to your addon folder.
I think..