  We compare systems with single giant planets to systems with multiple giant
planets using a catalog of planets from a high-precision radial velocity survey
of FGKM stars. Our comparison focuses on orbital properties, planet masses, and
host star properties. We use hierarchical methods to model the orbital
eccentricity distributions of giant singles and giant multis, and find that the
distributions are distinct. The multiple giant planets typically have moderate
eccentricities and their eccentricity distribution extends to $e=0.47$ (90th
percentile), while the single giant planets have a pile-up of nearly circular
orbits and a long tail that extends to $e=0.77$. We determine that stellar
hosts of multiple giants are distinctly more metal-rich than hosts of solitary
giants, with respective mean metallicities $0.228\pm0.027$ vs. $0.129\pm0.019$
dex. We measure the distinct occurrence distributions of single and multiple
giants with respect to orbital separation, and find that single gas giants have
a $\sim$2.3$\sigma$ significant hot ($a<0.06$) Jupiter pile-up not seen among
multi giant systems. We find that the median mass ($\msini$ ) of giants in
multiples is nearly double that of single giants (1.71 $\mjup$ vs. 0.92 $\mjup$
). We find that giant planets in the same system have correlated masses,
analogous to the `peas in a pod' effect seen among less massive planets.
