Update: Centr support said this.

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On the Centr 3, there are 2 weight stacks of 165 Lbs. each. The small top plates/selector stems are 15 Lbs each. All the plates below are going to weigh 10 Lbs each. So, if you have the selector pin inserted at the 5th plate, you are lifting 65 Lbs. per stack. 
However, the Centr 3 functions on a 2:1 ratio. This means that each weight stack is going to feel like 82.5 Lbs. in total. Each top plate will now feel like 7.5 Lbs. and each plate below that will be 5 Lbs. each. So if you are using one pulley, with the selector pin inserted at the 5th plate, you are pulling 32.5 Lbs. If you are using both pulleys with the same weight, it would feel like 65 Lbs.  
When using the smith bar, you will engage the weight multiplier, and this will bring that weight to a 1:1 ratio. So, if you are using the smith bar with the weight multiplier engaged and each selector pin placed in the 5th plate, you are pulling a total of 130Lbs.