  In the last few years many globular clusters (GCs) have revealed complex
color-magnitude diagrams, with the presence of multiple main sequences (MSs),
broaden or multiple sub-giant branches (SGBs) and MS turn offs, and broad or
split red giant branches (RGBs). After a careful correction for differential
reddening, high accuracy photometry with the Hubble Space Telescope presented
in this paper reveals a broadened or even split SGB in five additional Milky
Way GCs: NGC 362, NGC 5286, NGC 6656, NGC 6715, and NGC 7089. In addition, we
confirm (with new and archival HST data) the presence of a split SGB in 47Tuc,
NGC 1851, and NGC 6388. The fraction of faint SGB stars with respect to the
entire SGB population varies from one cluster to another and ranges from
$\sim$0.03 for NGC 362 to ~0.50 for NGC 6715. The average magnitude difference
between the bright SGB and the faint SGB is almost the same at different
wavelengths. This peculiarity is consistent with the presence of two groups of
stars with either an age difference of about 1-2 Gyrs, or a significant
difference in their overall C+N+O content.
