First Comparison of Ionization and Metallicity in Two Lines of Sight toward HE 1104–1805 AB at z=1.66Based on observations made at ESO, La Silla, Chile, the Anglo Australian Telescope, and the NASA/ESA HST, obtained at the STScI, which is operated by AURA, Inc., under NASA contract NAS5-26555. Also based on observations made at the W. M. Keck Observatory, which is operated as a scientific partnership between the California Institute of Technology and the University of California; it is made possible by the generous support of the W. M. Keck Foundation.