  Examination of loading the isotopes $^{85}$Rb and $^{87}$Rb simultaneously
into a shallow far-off-resonance trap (FORT) has revealed an unexpected
decrease in maximum atom number loaded as compared to loading either isotope
alone. The simultaneous loading of the FORT will be affected by additional
homonuclear and heteronuclear light-assisted collisional losses. However, these
losses are measured and found to be insufficient to explain the observed drop
in total number of atoms loaded into the FORT. We find that our observations
are consistent with a decrease in loading rate caused by inter-isotope
disruptions of the efficient laser cooling required to load atoms into the
optical trap.
