Build the circuit shown. With the multimeter you measure the voltage between the base of transistor T1 and the emitter of transistor T2.
Turning the potentometer P1 until the Darlington pair is fully saturated, you measure a base-emitter voltage of...
UBE = 1.30 V
This value is twice as high as of a single transistor. This is a disadvantage of the Darlington pair.
But what about the gain of a Darlington pair?