They aren't the same.
Like many other cable providers, they "rotate" the IP addresses.
If user A has 164.221.78.13 today, he will get another different IP (same subnet class) in a week or two (they're usually changed after two weeks, if memory serves).
Someone else will get user's A IP address at the same time.
Week 1: User A - 164.221.78.13. User B - 164.221.24.213
Week 3: User A - 164.221.20.79. User B - 164.221.78.13
You get the drift.
Is everyone's IP the same?
Yours too?
If so, something's really fishy going on...
Cable IP addresses can be "hijacked", but not shared so easily between many users at a time.
