3D object on different image target has debug

Hi

Can you help me, please

I have 2 problems with unity ar using vuforia. I have 2 images target and have set different 3D objects that will appear on those images target. (Different image target and different 3D object).

1. If I scan image target 1 the 3D object 1 will appear. Then, if I scan image target 2, 3D object 2 will appear.. but the problem is, there is some halo or cache of the first 3D object 1. (as shown in red circle in the image)

2. Sometimes if I switch the image target, other 3D objects will not appear. It only runs at first image target either 1 or 2. After the switch, sometimes 3D object will not appear.

Can you help me? I really appreciate and I would like to say a millions thanks in advance.

Thank you