Essentially, they were cousins? Much like how Yamnaya and Corded-Ware peoples were more or less the same, but had different haplogroups.IBM and Natufian are similar. They both sourced from the original stock of Mesolithic huntergathers of North Africa.
The IBM they samples had 1/3 ssa in them but that was just exclusive to those specific individuals. It is alien to North Africa because it was absent among the Natufians.