apoivre - You can do whatever you want with a RTW ticket including splitting it up and re-starting. The only restictions are usually the standard 1 stopover in each City and maximum 3 transits through a City. And of course you have to go in the same direction when crossing the Atlantic and Pacific.

There are a number of people on FT who have 2, 3 and 4 RTW's running at the same time. There is probably someone who has even more knowing FT. BKK is also a cheap place to start RTW's but not a cheap as CAI at the moment. Some start from CAI then start another one from BKK.