It sounds like you already know this, but Julii corys and Trilineatus corys are two different species, even though often lfs
' mistake one for the other. Considering how similar their markings are, I suppose that is understandable. Just be sure you have what you think you have; pictures of both can be found here
and if you click on the pic it pulls up a little info about each one. The description for the trilineatus gives a very good verbal comparison of what to look for if you are trying to distinguish a trilin from a true julii.