Not sure if it's a bug or not, I have two rings and one helmet, both rings add +2 to constitution, helmet +1, when I equip all of them I get only +2. If it's not a bug then it should be described somewhere imho.
Cheers

It's not a bug; the loading screen tips mention that item bonuses don't stack, I believe.

Yeah, t does mentions that they don't stack on the loading screen 

They don't stack, you only get the higher (+2). You should see what bonuses are suppressed in character panel.

Edited April 1, 201510 yr by Anelor

In the character screen, if you look at your currently active effects, you will see 

 

(suppressed) 

 

when items don't stack. So you always have a clear overview of what is and isn't stacking.

Thank you for your reply, I was just curious, haven't seen this text.

If they don't stack they should pop up the tooltip when stacking stats items being equipped. Not in the loading screen. Just saying.