13 Inch Dart GT Rims - Going In Circles

When I bought my '64 Dart GT (with 273 & 4-speed), it had two types of 13" wheels on it; one standard issue plain wheel (at left in the picture), and three with an open / slot type (at right). Were there two different styles of wheels used on the '64 cars ? Did the GTs or V8 cars have a different wheel on them than the other models ? Which is correct for my car ? I'm assuming the open / slotted type. My car originally had the dogdish caps. Were certain wheels used in combination with them ? Also, both of these wheels pictured have an extra hole (smaller) with the lug pattern. Are the wheels with these extra holes to be used on / aligned with holes on drums (fronts ?) for brake adjusting or something ? What was the purpose for them ?