If this is the case, then how was it fixed?
If that's how it works, then it's just a chain.
BLID 100 changes their name to Blockhead 101.
BLID 101 is purchased. His name starts off as Blockhead 102 (because Blockhead 101 is taken).
BLID 102 is purchased. His name starts off as Blockhead 103 (because Blockhead 102 is taken).
This repeats on and on.
But, let's say it gets to BLID 500 is purchased.
BLID 500 starts off as Blockhead 501 (because Blockhead 500 is taken). Before another purchase is made, he changes his name.
BLID 500 is now Blocklander-man (or whatever he chooses).
BLID 501 is purchased. His name starts off as Blockhead 501 (because Blockhead 501 is no longer taken).
BLID 502 is purchased. His name starts off as Blockhead 502.
The cycle is broken.
Or atleast, that's how it could break.