  Very deep ESO/VLT FORS1 and ISAAC images, as well as HST NICMOS2 data are
used to infer the nature of the quasar pair LBQS 1429-0053 A and B, either a
binary quasar or a doubly-imaged lensed quasar. Direct search of a putative
lensing galaxy is unsuccessful . Moreover, no galaxy overdensity close to the
quasar pair is found. A weak shear analysis of the field also fails at
detecting any concentration of dark matter and weakens the hypothesis of a dark
lens. The only sign of a possible lens consists in a group of 5 objects at z~1,
within a radius of 5'', from the quasar pair. Considering this group as the
lensing potential does not allow to reproduce the image position and flux ratio
of the quasars. Our deep R-band image shows a blue, extended object at the
position of quasar A, which is consistent with either being the lensed quasar A
host, or being an intervening galaxy at lower redshift. Unless future very deep
optical images demonstrate that this object is actually the lensed host of LBQS
1429-0053, we conclude that there is very little evidence for this quasar being
lensed. Therefore, we are led to declare LBQS 1429-0053 A and B a genuine
binary quasar.
