  We present a new SCUBA image of the cluster MS0451.6-0305, which exhibits
strong, extended sub-mm flux at 850 microns. The most striking feature in the
map is an elongated region of bright sub-mm emission, with a flux density of
>10 mJy over several beam-sizes. This region is apparently coincident with a
previously known optical arc (which turns out to be a strongly lensed Lyman
Break Galaxy at z=2.911), as well as with a newly identified multiply-imaged
ERO (Extremely Red Object) pair predicted to be at a similar, if not identical
redshift. By combing a detailed lensing model with deep images from HST,
Chandra, CFHT, JCMT, and spectra from the VLT, we conclude that both the
strongly lensed optical arc and ERO systems have properties consistent with
known sub-mm emitters. Using a simple model for the two sources, we estimate
that the multiply-lensed EROs contribute the majority of the flux in the SCUBA
lensed arc. Correcting for the lensing amplification, we estimate that the
inherent 850 micron fluxes for both objects are ~0.4 mJy. If the LBG and ERO
pair are truly at the same redshift, then they are separated by only ~10 kpc in
the source plane, and hence constitute an interacting system at z~2.9. Higher
angular resolution observations in sub-mm/mm will permit us to more accurately
separate the contribution from each candidate, and better understand the nature
of this system.
