  The charge ratio, $R_\mu = N_{\mu^+}/N_{\mu^-}$, for cosmogenic multiple-muon
events observed at an under- ground depth of 2070 mwe has been measured using
the magnetized MINOS Far Detector. The multiple-muon events, recorded nearly
continuously from August 2003 until April 2012, comprise two independent data
sets imaged with opposite magnetic field polarities, the comparison of which
allows the systematic uncertainties of the measurement to be minimized. The
multiple-muon charge ratio is determined to be $R_\mu = 1.104 \pm 0.006 {\rm
\,(stat.)} ^{+0.009}_{-0.010} {\rm \,(syst.)} $. This measurement complements
previous determinations of single-muon and multiple-muon charge ratios at
underground sites and serves to constrain models of cosmic ray interactions at
TeV energies.
