Sounds like a dumb question and I will be leaving out some information for reasons that may be clear to some and maybe not so to others. But anyway looking for guys who really know their compounds.
Hypothetical question...
Bottle A. contains Deca 200
Bottle B. contains test Prop 100
lets say both of these have been made using the same oil so they are the exact same colour and for some reason the labels have come off.
How can you tell the difference between A and B?