You could have gained more your second time. I am guessing, but your diet remained the same. I am doubting you added a lot more calories to your diet and sustained that amount to hold the mass on. That is required to get bigger each time, ya know.
Guys will gain a lot, and still remain eating the same amount and they wonder why progress comes to a hault or slows a lot. It's because your body needs further caloric intake if it is going to get bigger.
The entire notion of using any anabolic twice giving a lesser effect as a result of repetition is a myth. The bigger you get, the slower you gain. The bigger you get, the more calories you need.
If your diet is 4000 calories and you can't gain past 210lbs with it, all the steroids in the world aren't going to help you out. But move that 4000 calories to 4500 and bam, you are going to gain mass comparatively easy. Move it to 5000, and you will gain even more weight, but it may be a bit sloppy for a while. Over time your body just wants to eat that much and you are eating 25% more calories, and 25% more is a ton of potential for mass.
It's all in the diet bro. Not what anabolic you use.