Correct name for experiment aimed at confirming an alternative Hypothesis?
If you are doing a bunch of hypothesis tests in the first phase, you are likely to detect false positives unless you correct for multiple comparisons.

In the second phase, you commit to a particular intervention so multiple comparisons is not an issue.

You could call the first phase exploratory and the second phase confirmatory. But, there is nothing special about the experiment. You are simply applying a intervention and comparing its affects vs a control group. Your motivations or hopes don't make any difference.

But maybe I've misunderstood your experimental design. You aren't very clear in your description. Specifically, I don't see how the second phase is "rigged".

Further, if you are being scientifically honest, the goal of the second experiment shouldn't be to confirm the alternative hypothesis, but rather to see whether the null hypothesis can be rejected. The experiment would be successful no matter what you learn.