My personal favourite, least complex way is reading from an "in-memory" file.

$_ = q| 
abc:
  asdf1
  asdf2

def:
  asdf3

ghi:
  asdf4
  asdf5
|;

local $/ = "";          # or $/ = "\n\n";
open IN, '<', \$_ or warn "opening \$_ failed";

my $n; $n .= $_ for <IN>;

print "exact" if $n eq $_;
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If I wasnt too particular about the double-newlines, I would use split instead.