The title explains it all really.
Each shield should give my character +2 AC,. I've equipped two shields, so I should have +4 AC but this isn't happening.I assume it's because nobody often dual wields shields and wasn't thought of. Can/will this be fixed or do I just need to adjust my characters AC manually?

Thanks 

From the shield description:

You can benefit from only one shield at a time.

The character sheet mostly only follows the official rules.

If your group is using house rules, you will have to modify your character sheet either manually or with homebrew.