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First off let’s not confuse people calling a darlington pair an IC. A darlington pair could be two separate transistors configured as a darlington pair or it could be two transistors built into one package with only three pins, one each for Base, Collector and Emitter.
The LM317 is an IC with only three pins and is commonly referred to as a voltage regulator. The output of this IC is a darlington pair stage already built into the IC. So it appears that you don’t need a second darlington pair to connect to it.
Datasheet of the LM317 is available at the link below.