PEAR seems to not be able to handle multiple connections to different databases.  To illustrate, create two tables in different databases (can be on the same server, but different databases within that server).

include("DB.php");
$oneWrapper = new DB();
$oneDB = $oneWrapper->connect("type://user:pass@server/one");
printRes($oneDB->query("select count(*) from table_one"));
$twoWrapper = new DB();
$twoDB = $twoWrapper->connect("type://user:pass@server/two");
printRes($twoDB->query("select count(*) from table_two"));
printRes($oneDB->query("select count(*) from table_one"));
printRes($oneDB->query("select count(*) from table_two"));
function printRes($res) {
   if (DB::isError($res)) {
      echo "Error:  " . DB::errorMessage($res) . "\n";
   } else {
      $data = $res->fetchRow();
      echo "Result: " . $count[0] . "\n";
   }
}


This code will print out

Result:  0
Result:  0
Error:  no such table
Result:  0

Looking back at the code, you will see that $oneDB is now pointing at the $twoDB's database instead of its correct one.