If you want lines into strings:

my ( $key, %data );
while ( <FH> ) {
    if ( /^([^:]+):/ ) {
        $data{ $key = $1 } = $_;
        }
    else {
        $data{ $key } .= $_;
        }
    }
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If you want lines into arrays:

my ( $key, %data );
while ( <FH> ) {
    if ( /^([^:]+):/ ) {
        $data{ $key = $1 } = [ $_ ];
        }
    else {
        push @{ $data{ $key } }, $_;
        }
    }
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If you just want an array instead of a hash:

my ( $key, @data );
while ( <FH> ) {
    if ( /^([^:]+):/ ) {
        push @data, [ $_ ];
        }
    else {
        push @{ $data[ -1 ] }, $_;
        }
    }
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Update: and with a single array:

my ( $key, @data );
while ( <FH> ) {
    if ( /^([^:]+):/ ) {
        push @data, $_;
        }
    else {
        $data[ -1 ] .= $_;
        }
    }
[download]