Yeah of course... They have all the data for Party / Ladbrokes / Coral and other sites so cannot let someone self excluded from one play on another.
Stars recently notified about that too.
Quote:
If we can identify that you have an account with Paddy Power, Betfair or Sky Betting & Gaming (which includes Sky Bet, Sky Vegas, Sky Bingo, Sky Casino, and Sky Poker), and you self-exclude on PokerStars, then your self-exclusion will also apply to such other account(s).