the problem about two Object with Alpha material

In order to make two object translucent,I make the two object using the shader “Transparent/Diffuse”.
It does work exactly.
But when the two object are near each other,there will be some Flash surface.
If I use the “Transparent/cutoff/Diffuse”,the Flash surface will be missing and the translucent effect alse is missing.
How can avoid it?

A lot of things could be causing it. But in computer graphics, transparent objects need to have a clear order of “closer” and “further away” to draw properly. If you ever have one which is technically further away, but parts are closer and overlapping the other one, it will just look wrong.

Most common solution is not to put transparent things that close. Other methods are to break the larger object into smaller parts (but I haven’t done that – I don’t know if Unity will always draw an object and children together, which would negate the trick.)