Can the bin2hex value two different strings be the same?

Question

I am using bin2hex to create unique id's for my users as an Identifier and I don't want to connect to MySQL for checking repetition .

Answer 1

If the string is unique, the hex will be too, because it has the same contents presented in different format. Note that the hex will generally be about twice as long as your input string, so there could be performance/storage issues if you have lots of longer strings.