There are some buildings that you can only build once (for example, Statue of Kane and the Redeemer/Reclamator/Hexapod Facility). However you can actually build more then one. Get additional Construction Yards (build MCVs at your War Factory), then place the Construction Yards. You now have more than one building queue. Start making the building you want more than one of at all your Construction Yards. When they are done, place them. The more Construction Yards you have, the more statues or facilities you can make.
Scrin: Placing buildings in thunder storm
When playing as the Scrin in either multi-player, Skirmish or the Scrin campaign mode, it is usually not possible to place buildings within a thunderstorm produced by the Storm Tower. To get around this, power down the Storm Tower and place whatever you want next to it (another Storm Tower is recommended). This strategy will help improve your base defense.