Overmedication
Just imagine you have an illness and you are confronted by not one, but two doctors.
The first one after examination confirms your illness and gives you a bottle of pills - take one a day.
The second one then tells you to take twice the dosage.
You have two expert opinions here, so what do you do? One may be enough... but if it isn't, surely there is no harm in taking two? If there was, the second would not have prescribed that (I am assuming no malice and also no incompetence). So you take two, you get better.
The medication of the second doctor worked. News spreads, everyone starts taking two tablets instead of one. The same also happens for other medications.