It seems to be common practice to double up observations. For example, shortly before New Horizons flew by Pluto, several of its moons were discovered by telescopes as a concerted effort was put in because of the occasion.
Have other telescopes made systematic and dedicated observations of the field of view of the Kepler telescope? I imagine speculatively in this paragraph that such observations could've been part of a survey process to determine where to point Kepler out of a set of candidate FOVs to begin with. And once decided upon, that field more closely examined. Then during the Kepler mission persistently observed in order to help rule out noise from passing asteroids and binary and variable stars and to gather complementary data. To characterize transiting planets, it is important to characterize the stars they are orbiting, something which telescopes with other kinds of instruments can be helpful with. Those are just my speculations about why I would think that Kepler's primary mission was "doubled up" by other kinds of telescopes.
What are some of the preparatory, complementary or follow up observation campaigns that have been made of the Kepler field of view? Is Kepler's FOV now one of the most and best observed parts of the sky?