How to make two APEX cloths collide?

Current I’m trying to create APEX in my character
But the cloths doesn’t collide even I set the backstop offset…

Just like this :

&stc=1

Is there any way to make it looks like the demo video of APEX cloth?
Do I need to make the dress become doubleface or I have to merge them into one mesh?
Please someone give me some hints or help q_q