Wiring identical LEDs in parallel
Just because they are in the same consumer/retail/commercial package does not mean they are from the same production run, or same bin. They are not guaranteed to have the same diode properties for forward voltage or current or brightness. 

You can attempt to match them for current and brightness, but the simplest solution is to use one resistor per parallel circuit. Resistors are cheap and small. 

The typical efficient setup for white leds at full brightness 20mA @ 12 Volts is three leds in series with one resistor. Repeat for additional strings of three. You could do two per resistor if you adjust the resistor value.