Just an idea: add 4+ pixels of transparency around the 'Front-End' sprite, it looks like that texture is being bi/tri linear filtered into your circle sprite rendered image (if you are zoomed in or out, you might also be at a different mip level so you may need more than 1 pixel of source transparency buffer between the images.) Also if you want to do some testing/debugging before you try that, change the bottom of the Front-end sprite to all red pixels and see if that changes the color of the 'line' at the top of your circle sprite.
Okay... The line changed to red:
So, yeah... The solution is to cut every single object in the project... Not only one object should be cutted but every his neighboor on spritesheet, too. Sounds like a trip to hell, but I am starting to do that with hope that conditions which move objects wouldn`t be broken after this.
Thanks for a good idea for the experiment. Why I haven`t knew that before?