Use uniq from List::Util:

use List::Util qw{ uniq };

%teamAcctsUniq = map {
    $_ => [ uniq(@{ $teamAccts{$_} }) ]
} keys %teamAccts;
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Or you can assign the whole hash at once:

@teamAcctsUniq{ keys %teamAccts } = map [uniq(@$_)], values %teamAccts
+;
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