hello
1-i had the same problem one day, if your scene contains textures with alpha maps, e.g. trees, figures, etc...., rendering to exr or vrimg makes such problems, because the output will be brighter, you have 2 soluotins, even replace alpha textured geometry with real 3d geometry (proxy), or, use double sided material for alpha textured maps, otherwise, simple materials will have the same problem with you.
2-for anti aliasing, choose adaptive subdivision instead of DMC, if your poly count is too high use QMC.
3-if you are rendering exterior scene, dont use LC for 2nd bounce, use None, in the other side, change color mapping to linear, increase fnumber of vraycam and adjust gamma to be (1.8-2.2).
4-why dont try using HDRI background instead of vray sky, because HDRI is an exr type?
all above is my trial and error.
hope works......