[St00ne]

Wait, it worked for me after doing what is written in 1st post, and restarting the daemon.

'Old' SteamID player profiles are fully correct. It seems that the piece of data that was sent to the profile with the new SteamID, is now redirected to the main profile of a player.

I just have to reset the stats now, or wait 28 days for the player profiles which are not used any longer to be hidden.
If I reset the stats and I still have two profiles, that won't be a real problem as long as one profile is completely empty, and thus, not ranked/hidden.

I suggest Killer0561 to try again the modifications of 1st post.

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