10 months ago - Juber - Direct link
Just scroll further and you will see the building again with the other boost.
The reason for that is, that it does not provide a combined boost, but rather 2 separate boosts: One for attack and one for defense. Therefor it is displayed with 2 entries.  
10 months ago - Juber - Direct link
OK, so this is currently working as intended, meaning while not ideal, it is not a bug.
You could create an idea to improve it, but please remember to give details on how to do it! :)