Poco- hope i don't offend w/my direction; I don't know how much you know about electricity in RVs so my approach is to err toward safety.
If your gen is 6500 working watts @ 120/240V then you have 6500/240 = 27.3A per leg available which would run most 2-AC RVs. If your gen is 120V, then you have 6500/120 = 54.6A total, split between two 30A twist lock receptacles. You state one is 120/240V so I'm guessing the gen is 240V and you can run either one 120V 30A cord, or one 120/240V 30A cord, but not both. This sounds like a construction gen, possibly of an older design which is no longer made due to the exact nature of your question (i.e. it leaves the untutored operator with the possible conclusion you can run two legs @ 30A plus one at 30A).
From your profile (you should put this in your signature so folks don't need to look it up) it looks like you have a 5er. You mentioned my "50 amp service" which I'll assume is the service on your coach. If that isn't right, then disregard what I'm saying.
The 50A service is two legs of 120V, 180° apart, for 240V if you connected the two thru an appliance or volt meter. You never see 240V appliances on the usual RV, so effectively mfgr's wire some 120 stuff off one leg including the 1st AC, and the second AC unit off the 2nd leg. Assuming you can run your rig on 30A with no problem other than not having the second AC (here I have no idea what loads your King of the Road has otherwise, dishwasher, washing machine, treadmill, salvage car crusher), you should be able to power both ACs plus some other stuff easily, if you wire the power correctly to the 50A service on your rig!!! That's in italics because here you are messing where a lot of lawn-chair DIY'ers shouldn't, tho a careful and attentive electrician could. Get your prongs to spades crossed & if all goes well you will have no more than an insurance claim on your hands, & if all doesn't go well you could have a real bad time; get it done right & all is COOL. HOWever:
You mentioned you have only one 30A push breaker protecting something. That could be a dual breaker with a single push button reset, with the 120V 3-prong outlet double tapped off one side of the dual and the 4-prong 240V tapped one leg off each side of the dual.
If you are good w/a volt meter, start the gen & probe the outlets to figure out what the real available voltages are. If you have 240, then check out the breaker wiring to see if both legs have a breaker. If you can't do that based on the suggestion, your electrical DIY skills aren't up to this analysis and I'd suggest finding an electrician who can make the tests, as you need a qualified conclusion before moving ahead.
Hope this helps.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project