Thank you very much for your reply,

I know for definite both variables are set and are the same, eg:

[code]set $var1 'yes';
set $var2 'yes';
if ($var1 ~ $var2) {
...
}[/code]

Returns:
[code]*1 "$var2" does not match "yes"[/code]

So seems like the second variable is considered a string and not a variable.