The stringified form also depends if the values began as strings or numbers.

$x = '1e-3'; 
$y = 0.001; 
if ( $x eq $y ) { print "$x and $y are equal.\n" }
else { print "$x and $y are not equal" }

print "\n";

$x = $x + 0;
if ( $x eq $y ) { print "$x and $y are equal.\n" }
else { print "$x and $y are not equal" }
[download]

Result is:

1e-3 and 0.001 are not equal
0.001 and 0.001 are equal.
[download]

In the first comparison, $x is a string. In the second comparison, $x is numeric before it is stringified for comparison.

The Scalar::Util documentation is useful here. https://perldoc.perl.org/Scalar/Util.html#isdual