Offline-mode (cracked) servers and online-mode=false proxies give every player the UUID UUID.nameUUIDFromBytes("OfflinePlayer:" + name). It is case-sensitive: Steve and steve get different UUIDs. Looking for the real Mojang UUID? Use the Player / UUID Lookup.
| Name | Offline UUID |
|---|
Accepts 069a79f4-44e9-…, 069a79f444e9…, NBT [I; 1, 2, 3, 4] or two longs most, least.
// Java Reference