What I tend to do as a standard to my car is that " If the item and or fliud is unknown best to change it with a known item."
This way I am able to control what goes into the car and not to worry anymore. In the case of clutch and brake fliud fresh is best naturally. If the fluid has been sitting around in the garage or in a car for a few years they tend to absorb water leading to corrosion in the lines down the track.
MoonButt