Rabbit Hole states:
"When Rabbit Hole is installed, you may search your stack for another copy of Rabbit Hole and install it by paying its install cost. Shuffle your stack,"
My question is could you use the second copy of Rabbit you install to then search for a third copy (should you have two Core Sets) and install it. So you effectively use a single Rabbit Hole to play all three copies, should they be in your stack of course.