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The *real* work you have to do *is* double because the hollow
cylinder ends up with equal amounts of translational and rotational
kinetic energy.
But the *pseudowork* you have to do is only half the real work
because it only considers the translation of the center of mass.
Friction does the other half of the pseudowork of getting the
cylinder moving.
That is, if you want to know how tired you're going to get when you
pull on the string, ask about the real work.
If you want to know how fast the cylinder is going to end up moving,
ask about the pseudowork.