Two long range cannons on the same planet?
I remember in Entrenchment wondering if I could build two Kostera Cannons on the same planet, and finding it odd that I can have up to 35 tactical slots- but the cannon uses 18.
Diplomacy changed that with the shared buffs between civilizations. One of them allows both me and an ally player to have 4 free extra tactical slots, effectively defeating the number chosen for previous versions. I'm afraid the developers meant for it to be impossible to have two cannons on the same planet, but have missed this.