I went ballooning in Cappadocia just last month, and on the day I flew there were nearly 40 other balloons in the sky. I don't have sufficient frame of reference to say whether that is a lot, but it is more than it used to be - the operator I flew with told me the number of balloons that rise up over the valleys of Cappadocia each morning has grown over the years.
Either way, it caused no problems on that occasion. The pilot of our balloon was in radio contact with other pilots to keep track of where we were in relation to other balloons. They would often radio to check that there was no balloon above us before we ascended.
Nor is it unusual for a number of balloons to take off in the same airspace - take a look at photos from the many festivals all over the world, such as the famous one in Albuquerque, New Mexico.
Suffice to say that the incident in Cappadocia is as out of the ordinary as it is tragic. We will have to wait for more information from Explore and from the Turkish authorities before we know exactly what lay behind it.