Not sure when FWC added the portable connector on the back, but I'll assume your 2012 Fleet does not have one. If you do have one, just plug the portable solar panel into it (after checking polarity).
Unless you have a lot of solar panel watts, you should be able to connect the second panel to your existing charge controller.
Add up the wattage of both panels and divide by 12. This is your maximum solar panel current output. Your charge controller needs to be rated for this much current or more.
If you have a 160 W panel and a 100 W panel, your charge controller needs to be able to handle 21.67 amps. In reality, you will never get 100% out of your panels, so a 20 Amp charge controller can handle 260 W of panels. Look at your charge controller rating. If it is less than 90% of your maximum current output of the panel, upgrade, Upgrading is likely to be almost as cheap as a second charge controller and a much better way to go.
If you upgrade, consider getting an MPPT charge controller. They are more expensive than the PWM charge controllers, but they are much more efficient. And for MPPT, go with Victron Smart Charge Controllers, they are well worth the additional cost over Renogy and other brands.