Digit 2 Appended to Field Name on Column in Entity Field Query
If you use Email module, use email instead of value, because the module store the value in field_name_email not field_name_value like other field like text ... 
So you Query should be like:

$dup_query1 = new EntityFieldQuery();
$dup_query1-&gt;entityCondition('entity_type', 'node') 
    -&gt;entityCondition('bundle', 'fair_participant')
    -&gt;fieldCondition('field_last_name', 'value', $last_name , '=')
    -&gt;fieldCondition('field_first_name', 'value', $first_name , '=')
    // use email not value.
    -&gt;fieldCondition('field_email', 'email', $email , '=');

$fpmatch_fandl_email = $dup_query1-&gt;execute();