DOF strange doubling effect

[guenther Malek]

in the picture attached you can see a strange doubling effect occuring behind

the blurred letters.

First i thought it´s a refraction issue but IOR is 1,0 and they have no thickness.

any idea, where this comes from?

 

[jurellranzijn]

try scroll through the render ellements. maybe one of them highlight the problem.

reflection,

refraction,

all these elements