This happens if someone requests a merge of two player profiles - presumably because they believe they are the same player - but both profiles have a registered account associated with them.
We can't merge these profiles because we can only have one account per player profile and, importantly, it's sometimes an indication that they are not the same player after all. It's much harder to unstitch incorrectly merged players!
If you see this message and you are the player in question and you can confirm that both profiles are yours then please contact us and let us know which account you would like to keep. We can then remove the other one and merge your two profiles.
We can let you know which accounts are involved if you can't remember both of them. It's likely one of them is very old and you've forgotten all about it!