For the "Who's got the porn" experiment I don't think test takers knowing which group they were in would make much difference. My understanding is that both groups would be told they were being tested for ESP. However, one group is told hot stimulating pictures are mixed in with regular pictures, and the other group is told there are only regular pictures. According to the article, the group with no added incentive (from erotic pictures) to choose correctly had accuracy which would be expected, at about 50%. However, the group with the stimulating pictures was able to beat the 50% threshold. Presumably, the brain of those test takers had more incentive to use all resources available to be correct, including any extrasensory ones...
As such, test subjects knowing they are in the group with the erotic pictures should still be able to beat the 50% threshold.
Edit: Actually, I'm reading through the actual experiment and it appears all 100 sessions used both erotic and nonerotic pictures of varying arousal value. Also, both the position of the picture and the picture itself were not actually chosen by the computer until after the test taker made the choice, although they were told differently, making it a test for a future event. So, yes, I think we would already be compromised for trying to recreate the test.