You can't know when to quit
http://www.reddit.com/r/Bitcoin/comments/1suwzo/bitcoin_casino_justdice_highroller_nakowa_loses/
Here is a post from September 2013 from Nakowa himself. At this point he estimates that he was up 6,000BTC. He was upset because JD lowered the maximum bet from 1% of Bank to .25% of Bank.
http://www.reddit.com/r/AMA/comments/1my8fc/im_the_whale_on_justdice_id_love_to_answer/
JD has raised the max bet to .50% of Bank today.
To the best of knowledge, the only real reason to play under different names is so that the casino isn't spooked and lowers the maximum bet. Other than that, I can't see any real advantage.
The owners of the brick and mortar casino, the Golden Nugget, in 2004 struggled with this same problem very publicly as they were being filmed for a reality show by the creator of Survivor. They kept their limits very high when they took over as owners to attract the whales, but then one got lucky after they were operating for 9 or 10 months. The whale took the casino for $8.5 million in two weeks. He then packed his bags and lost it again at another casino. Statistically you would eventually make the money back, but you still have to meet the loans by investors. The owners reluctantly had to cut back their maximum bet.
Players like to play under different names to "change their luck" as well