If im not mistaken the "id tool" shows what ID the person has equipted. I could be wrong tho but I coulda sworn one day when i was bored and did it it showed a few people with the same id. Just found a quote...
Quote:Command: /delignore <id> [<id2> <id3> ...]
Description: Deletes characters from the ignore list. Banned ids are displayed in the /ignorelist command. Warning these are different ids then those displayed by /ids command...
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Command: /ids
Description: Displays IDs of all online players.
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Command: /id
Description: Displays your own ID.
So yea i think its the id the person has in thier hold