Maybe they changed their name to that after entering the game?
i can repeat the commands, the name still is wrong with rcon status
Probably, I should have put the rcon status answer in the middle so everyone can see that this is not about unlucky timing. As I said, issuing "rcon status" again after those three rcon commands gave me the same wrong name for the player while repeating sv player always gave the right one. Actually, I would have never noticed if I had not tried to automatically extract all information from both, the sv players and the status command, and put them together. This sometimes fails because status gives a different name for the same player number.
I just found a way to reproduce that bug:
Go to a server.
Change names until the server doesnt allow you to change it anymore by just ignoring your namechange.
(for me, changing "1" to "2", "2" to "3", "3" to "4" and "4" to "5" worked, but the server did not apply "5" to "6")
rcon status will give the name that you tried to change to lastly / the value of your local "name" cvar ("6")
rcon sv players will give you the name you had and still have ingame because all name changes after that were not accepted by the server. ("5")