Dupes stuck in Pharma chambers who have slimelung will not actually take Placebos. They try, though, if the power is flickering. So they'll get out of their Pharma Chamber, grab a pill, start to eat it, and then immediately run back into the pharma chamber after dropping the pill when the power is back on. This appears to be a pattern due to getting brown outs, where they'll try to eat the pill, then the power comes back on, and they run for the chamber again.
Steps to Reproduce
Dupe, Slimelung, Pharma Chamber, and a Placebo. Mix in a regular power problem. Wait and watch.
This issue has not been confirmed by a developer yet.