2 images as planes, one of them shows incorrect control for alpha I imported image as planes after enabling the add-on.
In First image , I have imported Image A as the BG and the alpha is numeric value and can be used to reduce opacity.
In second image, I have imported Image B as the BG but here I am not getting an alpha value to manipulate.
Based on @susu comments here is the nodes&gt;Base Color

I further went ahead and added a proper plane and using material I added the image as material. Doing the same you can see I get controlable aplha value. What I don't understand is why is the image coming out looking grey??
I exaggerated the problem due to lack to knowledge to application. I just needed to add BG's which can be reduced in transparency.
I was given simple solution of add Image as refrence. It is easy transparency with no grey etc issue.
Importing image as plane creates material complications which for SB work are unnecessary.
Thanks for taking the time out to answer.