Yes Susie is saying (correctly) that numbers are not unique so as in your example the number 1 could appear for AF, EU and OC.
So, to address the selectees/holes/Case Number issue.
The holes are indeed for disqualified entries. So, taking Africa for example, that has a highest case number of around 116,000 - there are only 61942 selectees for AF region. So, what happened is that they selected 116,000 people in the AF region knowing that there would be something around 50% fraud cases (they would know the percentage roughly). The Case numbers are assigned to those 116k "winners" but then 54,000 entries of the 116k were disqualified - leaving the 62k selectees that were notified. The disqualified entries are never notified (but probably blacklisted for following years).
So - in AF region the numbers move fast because around half the numbers are holes. Out of the 62k selectees the need to allocate about 24k visas (including spouses and children). In reality we don't know the global allocation split between the regions so this 24k figure might vary somewhat.
I have posted previously about the low response rates and the denial rates, so it will take many more than 24k selectees to allocate the 24k visas. The only issue is how many of the 62k will return their forms, or turn up for interview, or qualify for the visa - none of which we know yet - although we could make some educated guesses based on previous years. I think I'll spend some time on that tomorrow...