  The radio-quiet quasar BR1202-0725 (z=4.695) is a remarkable source with a
bright Northwest (NW) companion detected at submm and radio wavelengths but
invisible in the optical. In the absence of amplification by gravitational
lensing, BR1202-0725 would be the most luminous binary CO and FIR source in the
Universe. In this paper, we report observations with the IRAM Plateau de Bure
interferometer of BR1202-0725 in the redshifted emission of the CO(5-4) and
(7-6) lines, the [C I](3P2-3P1) line, a high angular resolution (0.3 x 0.8
arcsec) 1.3 mm map of the rest-frame, far-IR dust continuum, and a search for
the CO(11-10) line. We compare these results with recent ALMA data in the [C
II] line. Both the quasar host galaxy and its NW companion are spatially
resolved in the molecular line emission and the dust continuum. The CO profile
of the NW companion is very broad with a full width at half maximum of 1000 +/-
130 km/s, compared to 360 +/- 40 km/s for the quasar host galaxy to the
Southeast (SE). The difference in linewidths and center velocities, and the
absence of any lens candidate or arc-like structure in the field, at any
wavelength, show that the obscured NW galaxy and the SE quasar host galaxy
cannot be lensed images of the same object. Instead, we find morphological and
kinematic evidence for sub-structures in both the NW and SE sources. We
interpret these results as strong indications that the BR1202-0725 complex is a
group of young, interacting, and highly active starburst galaxies.
