Hab labs have diminishing returns? 3% + 3% = 5%

[lightvsdarkness]

When you place science lab on a space stations it says that it boosts relative science by 3%. But when you place 2 modules total boost becomes 5%. What? Why?
Diminishing returns on habs? I'm pretty sure the game does not tell you about this mechanic!

[Lawlman Griff]

The game says hab stacking penalties only kick in at a total of 50% so I am thinking this may be due to not having the upkeep space resources.

[corisai]

You get a penalty if doing 2+ research in same field in same time. Projects are included for that too.

[lightvsdarkness]

I think I figured it out. Bonus from hab labs is 2.5%.
The game just rounds it to 3%, which is very misleading.