Dual Boxing
 

Is playing two accounts on the same computer allowed?

no

Thank you

unless 1 account is on green/red, and another is on blue

No. You will get punished for doing so. If you have two people in your household who want to play P99, you need to get an IP exemption, and then have those two people play on separate computers. However, if you have an IP exception and attempt to use it to duo box, you will be punished if you get caught.

EDIT: Except for what Skarne said. You could play a single character on Red, Green, and Blue simultaneously if you wanted, but you couldn't duo box two characters on one server.

yeah thats the official line

the truth is far stranger

Yes, there are people who box since you can get around IP checks these days. But it isn't too common from what I have seen. It is usually pretty obvious when people are doing it, and they generally get reported (and therefore stop boxing). You may see the occasional boxer trying to farm some really remote camp nobody goes to, but it isn't rampant or disrupting any popular zones/camps from what I can tell. Not sure about Green though, since I don't play on it.

The official line for green is that one infraction of the boxing rule is a permanent ban.