How come they say this pill duro extend is not good for u when i get cialis from my doctor an it has the same ingredient in it. sildenafil?

Not the same: They have related ingredients but not the same ingredient, but that's only part of the problem. One is a tested, fda-approved prescription medication (which means there has been scientific research, analysis, and strict quality controls). The other sounds like an imitation item that was sold to consumers under the pretense that the item was safe and beneficial.