---->0702995-42.2017.8.01.0002 being the number i want to use to batch clean the document, keeping only the first time it found, completely wiping out the rest. [underlined emphases added]

I'm also confused by your OPed statement of requirements. I will concentrate on the above quoted section therefrom, so maybe something like:

c:\@Work\Perl\monks>perl -wMstrict -le
"use Data::Dump qw(dd);
 ;;
 my @lines = (
   'line 1 this line has no Foo number: keep',
   'line 2 Foo something 1234-12.3 other 123 first valid keep',
   'TOSS 3 Foo toss this 1234-12.3 line 123 DELETE',
   'line 4 Foo not same 1234-12.3 offset 123 line keep',
   'line 5 Foox not tag  1234-12.3 same offset 123 keep',
   'line 6 has no Foo number: keep',
   'line 7 Foo yyyy xxx 1234-12.3 this line keep',
   'line 8 Foo xxxx zzzz 1234-12.4 different n keep',
   'TOSS 9 Foo kill this 1234-12.3 one DELETE',
   'line 10 no Foo number: keep',
   );
 dd \@lines;
 print qq{\n};
 ;;
 my $strange_n = qr{ (?<! \d) \d+ - \d+ (?: [.] \d+)* (?! \d) }xms;
 my $toss_tag  = qr{ \b Foo \b }xms;
 ;;
 my $rx_can_toss = qr{ \A .+ $toss_tag \D* ($strange_n) }xms;
 ;;
 my ($valid_was_seen, $sn, $sn_offset);
 ;;
 my @keep_lines;
 LINE:
 for my $i (0 .. $#lines) {
   my ($sn_seen, $this_sn, $this_sn_offset) =
     map { $_ ? (1, $1, $-[1]) : () }
     $lines[$i] =~ $rx_can_toss
     ;
   if ($sn_seen) {
     if ($valid_was_seen) {
       next LINE if $sn eq $this_sn and $sn_offset eq $this_sn_offset;
       }
     else {
       ($valid_was_seen, $sn, $sn_offset) = (1, $this_sn, $this_sn_off
+set);
       }
     }
   push @keep_lines, $lines[$i];
   }
 dd \@keep_lines;
"
[
  "line 1 this line has no Foo number: keep",
  "line 2 Foo something 1234-12.3 other 123 first valid keep",
  "TOSS 3 Foo toss this 1234-12.3 line 123 DELETE",
  "line 4 Foo not same 1234-12.3 offset 123 line keep",
  "line 5 Foox not tag  1234-12.3 same offset 123 keep",
  "line 6 has no Foo number: keep",
  "line 7 Foo yyyy xxx 1234-12.3 this line keep",
  "line 8 Foo xxxx zzzz 1234-12.4 different n keep",
  "TOSS 9 Foo kill this 1234-12.3 one DELETE",
  "line 10 no Foo number: keep",
]

[
  "line 1 this line has no Foo number: keep",
  "line 2 Foo something 1234-12.3 other 123 first valid keep",
  "line 4 Foo not same 1234-12.3 offset 123 line keep",
  "line 5 Foox not tag  1234-12.3 same offset 123 keep",
  "line 6 has no Foo number: keep",
  "line 7 Foo yyyy xxx 1234-12.3 this line keep",
  "line 8 Foo xxxx zzzz 1234-12.4 different n keep",
  "line 10 no Foo number: keep",
]
[download]

(And in addition to an SSCCE, in future please also consider How to ask better questions using Test::More and sample data.)

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.