As documented, the default for the first argument of split is ' '. ("As a special case, specifying a PATTERN of space (' ') will split on white space just as split with no arguments does.")

$ perl -MData::Dumper -e'
   $_="   56  1752.eps a b";
   print Dumper split;
'
$VAR1 = '56';
$VAR2 = '1752.eps';
$VAR3 = 'a';
$VAR4 = 'b';

$ perl -MData::Dumper -e'
   $_="   56  1752.eps a b";
   print Dumper split " ";
'
$VAR1 = '56';
$VAR2 = '1752.eps';
$VAR3 = 'a';
$VAR4 = 'b';
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The next problem is that "2" is wrong for the third argument. You'd want to use "3" and ignore the last value returned.

$ perl -MData::Dumper -e'
   $_="   56  1752.eps a b";
   print Dumper split " ", $_, 2;
'
$VAR1 = '56';
$VAR2 = '1752.eps a b';

$ perl -MData::Dumper -e'
   $_="   56  1752.eps a b";
   print Dumper split " ", $_, 3;
'
$VAR1 = '56';
$VAR2 = '1752.eps';
$VAR3 = 'a b';
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Solutions:

for (@data) {
   my @a = (split)[0,1];
   my @a = (split " ", $_, 3)[0,1];
   my ($x, $y) = split(" ", $_, 3);
   my ($x, $y) = split;
   ...
}
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split is optimised so that it doesn't do any unnecessary work for the last one. You could also avoid split entirely.

   my ($x, $y) = /^\s*(\S+)\s+(\S+)/;
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