I get those on my blueberry bushes as well, but they're still growing and producing. I have no idea what they are, though.

Same here. I've noticed similar spotting on some of my plants both this year and in previous years, and I've come to suspect that it might be environmental/cultural as opposed to disease. I wouldn't worry about it too much. Just to be sure we're comparing apples to apples, are the spots visible on both sides of the leaves?

septoria leaf spot, I too get it here on my BBs on occasion, nothing to worry about, damp conditions are most likely the cause.

Ok, it has rained a bit here lately, so that's probably it.

It's hard to tell from your photos, but one of the hallmark signs of septoria is a whitish or ivory dot at the center of the spot. I don't know enough about it to say whether that feature is always present, but, if you do see it, then that's a good indication that it's septoria.

Two of my Blueberries (Climax & Brightwell) have severe Red Spots on both front and back side of the leaves.

I appreciate if someone could help on this. Below picture has both front and backside of Climax.

Thanks