  We report the serendipitous discovery of two strong gravitational lens
candidates (ACS J160919+6532 and ACS J160910+6532) in deep images obtained with
the Advanced Camera for Surveys on the Hubble Space Telescope, each less than
40 arcsec from the previously known gravitational lens system CLASS B1608+656.
The redshifts of both lens galaxies have been measured with Keck and Gemini:
one is a member of a small galaxy group at z~0.63, which also includes the
lensing galaxy in the B1608+656 system, and the second is a member of a
foreground group at z~0.43. By measuring the effective radii and surface
brightnesses of the two lens galaxies, we infer their velocity dispersions
based on the passively evolving Fundamental Plane (FP) relation. Elliptical
isothermal lens mass models are able to explain their image configurations
within the lens hypothesis, with a velocity dispersion compatible with that
estimated from the FP for a reasonable source-redshift range. Based on the
large number of massive early-type galaxies in the field and the number-density
of faint blue galaxies, the presence of two additional lens systems around
CLASS B1608+656 is not unlikely in hindsight. Gravitational lens galaxies are
predominantly early-type galaxies, which are clustered, and the lensed quasar
host galaxies are also clustered. Therefore, obtaining deep high-resolution
images of the fields around known strong lens systems is an excellent method of
enhancing the probability of finding additional strong gravitational lens
systems.
