Marc,

even if you are holding two different tickets for mco-lax and lax-ppt, your luggage should be checked throu all the way from mco-lax-ppt. at check-in at mco just present the two tickets and ask to get your luggage tagged checked throu all the way. luggage will be x-rayed at mco and you will not see your luggage again untill ppt. you do not have to pick up the luggage at lax and re-check luggage at lax.

at mco they can check your luggage throu all the way, but at mco you can not check in for the lax-ppt flight: means you get a luggage tag for mco-lax-ppt, but your boarding pass is only for mco-lax. so you have to check in at lax for the lax-ppt flight only to get a boarding pass for the second trip.

enjoy your trip and a luggage free day at lax

cheers