Maybe this answers your question:

$val eq '2'
String compare string value of $val with string '2'.

$val == '2'
Convert string '2' to number, and numerically compare with numeric value of $val

$val == 2
Compare numeric 2 with numeric value of $val

If a string starts with a number, its numeric value will be that number. Consider the following examples:

$ perl -e "print 'a' == 'b'"
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True because 0 == 0

$ perl -e "print 'a' == '1b'"
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Not true because 0 != 1

$ perl -e "print 'a' == 'b1'"
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True because 0 == 0

Liz