It's not clear what the OP means by "1st 2 digits":

1. 1st 2 chars

if( substr($v1, 0, 2) eq substr($v2, 0, 2) )
[download]

2. 1st 3 chars where 2nd char is '.'

if( (substr($v1, 0, 3) eq substr($v2, 0, 3) ) && 
    substr($v1, 1 ,1) eq '.' && substr($v2, 1 ,1) eq '.' )
[download]

3. 1st 3 chars where 2nd char is anything

if( substr($v1, 0, 3) eq substr($v2, 0, 3) )
[download]

Cheers
Chris