This oughta do it. 
my $str3 = 'ATGATG';
my $str4    = 'ATGATG';

my $catted = "$str3 $str4";
$catted =~ s/(.*)(.+) (?=\2)/$1/;

print "$catted\n";

[download]
Make the + a {2,} to specify 2 or more character minimum overlap.
Caution: Contents may have been coded under pressure.

In reply to Re: Merging Two Strings by Roy Johnson
in thread Merging Two Strings by monkfan

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