I have read and tested my code but I don't quite understand the output in 2 cases, will you explain?

I get two different output here from a single regex expression and the difference is a space between what I assigned to be my $1 and my $2 captures

I have googled this and read thru perl tutorials and I have found no real explanation that can answer my simple question, perhaps you can help?

s/^(.*)+([^ ]+)$/$2, $1/; #$1 is anything that starts is 1st name so /
+^(.*) and $2=anything else after

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this worked, please note the space between $1 and when I try to capture the $2 value...I only found this worked because I fat fingered it while looking for the reason my first try didn't work..,I ended up doing it differently to capture right last name but I still have need to get answer on this 

s/^(.*) +([^ ]+)$/$2, $1/;

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entire test code that gives me an error for demo 

use strict;

my @cognome = last_name_first("leonardo Da Vincy","Raffaello da Urbino
+");
print join(";",@cognome);
sub last_name_first {
    my@names=@_;
    foreach(@names){
      s/^(.*)+([^ ]+)$/$2, $1/; #$1 anything that starts is 1st name a
+nd $2=anything else after..FAIL!
     #s/^(.*) +([^ ]+)$/$2, $1/; #works... space seems to do it,why?
    }
    return @names;
    }

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In reply to need help with explaining the output by perlynewby

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