Building bonus (max passengers/population) stacking ?

Hi, I'm sorry if the question was already answered somewhere or if it' the wrong part of the forum for a such question.

In the game, there is some build providing more than periodic "gold/passenger".
Example:
White house provide +20 Max population
"Extraterrestrial Legacy" (I've only the name in french) provide +20 Max passengers

If I build 2 or more building of the same type, is the bonus are also stacking or is it only the first one that provide the bonus ?

Example:
1 "Extraterrestrial Legacy" => +20 Max passengers
2 "Extraterrestrial Legacy" => +40 Max passengers

Thanks for your attention

Hi - yes, they do add up but most buildings from missions can only be got once. Many of the rest (e.g. alien statue, space monument, Aztec pyramids) can have up to 10.

Yes I saw that most of special event building can only be got once.

Thanks for the answer, I'll collect some alien statue (I was quite far with my translation of the french name )  héhé !