i have notice (yesterday) that some players (i wont say how many) enter at LG with different nicks and that is not the strange thing...they play against themselves!!!
I found myself, few months ago, that one of my opponents have multiple accounts. He defended himself, by telling me that every accounts was intended for one single game, like Go 9x9, Go 13x13 etc. But, initial intentions were forgotten :), and the accounts played against each other...
As for masturbation, one of the reason for it (as doctors tell us) is to "discover yourself", your sexual stimuli. I don't see any relevant similitude to playing GO against yourself :)))
There are two different ways to play against yourself:
You can invite yourself to a game. This is a nice way to test things. The game will be unrated.
You can create several accounts, and enter all in the same tournament, making sure that one of the accounts win all the games. This will artificially increace your rating, and should be illegal.
The only thing this second, "cheating" way achieves, though, is an increased rating. In the end, that only gives those who beat the cheaters higher rating later, it surely doesn't make them better players! :-)
I personally find the idea of entering the same tournament twice crazy. I will occasionally have a game of go with myself using a goban, and I'd prefer to think of it as study rather than masturbation.
You say it should be illegal to enter the same tournament twice? I see this as tricky to enforce, for instance: Say I enter a tournament and my wife decides she wants to enter the tournament too -- will that be seen as me playing against myself? . Say I want to play some people at work -- it might be easier for me to register multiple accounts than have them register seperately. Again, it could easily look like I'm playing against myself.
So, I agree 100% that it is inappropriate to artificially inflate your rating. However, I don't think you're going to be able to enforce it very easily. To pick one random example, the way KGS handles this is to start new players with a rating of ? so their first games barely affect the rating of their opponents. This doesn't prevent the problem, but it makes it an awful lot harder to inflate your rating -- you not only have to create multiple accounts, you have to win lots of games with them all to get a good rating. For instance, if Lee Sedol decided to start playing go on KGS, he would start at ? instead of 20k, and he would not drop the rating of his opponents when he beat them.
i initially created a second account for myself because my go rating was too low, and not advancing quickly enough. i have now discovered that this allows me to play opponents in 2 games at once, at different handicaps. this is intrinsically quite interesting. and the main advantage of entering twice the same tournament. its true this leaves a dummy game with myself; not particularly interesting but hardly a heinous crime. its true that i can 'choose' who wins this game for my own benefit, but so what. it may help give me the privelige of waiting 8 months for the next stage - big deal!