use strict;
use warnings;

my %res;
while (<DATA>) {
	chomp;
	my ( $name, $date, @rest ) = split /\t/;
	push @{ $res{"$name\t$date"} }, @rest;
}
for my $key ( sort keys %res ) {
	my ( $name, $date ) = split /\t/, $key, 2;
	print "$name,$date:", join( "|", @{ $res{$key} } ), "\n";
}

__DATA__
nick	20/5/1950	one
john	18/2/1980	two	two and a half
nick	19/6/1978	three
nick	20/5/1950	four
nick	12/9/2000	five
john	15/6/1997	six
nick	20/5/1950	seven	eight

##</code><code>##

john,15/6/1997:six
john,18/2/1980:two|two and a half
nick,12/9/2000:five
nick,19/6/1978:three
nick,20/5/1950:one|four|seven|eight