I'm currently a Lt Cmdr 7 Engineer on a Science Vessel (so T1 ship - If you count the Miranda as T0) and when I equip Dual Disruptor Banks, my ship fires it's disruptors from...
Actually, the forum standard is to refer to these ships as T2, considering Tier 1 to be the Miranda / Light Cruisers.
Yep, this is a known issue. I'm really hoping the devs circle back and fix a lot of these minor anomalies in the ships. But I have a feeling they won't get to that for a while since there's a lot of other more pressing issues currently.
For more information about Engineering Reports, see the "What are Engineering Reports?" thread at the top of the Forum.
Klingon ship customization for T0 and T5 ships
This is where I got the T0 concept Seems the Devs use T0-T5 may be a typo...