You'll have to pay twice, but you can save two usernames on one computer. Switch when you open the launcher.
Yes it can.
You can install one dropbox client in one computer. If you want use two Dropbox accounts then sync 1st account and after that log-in to other dropbox account.
If I understand you right, you can access any amount of accounts on one computer, it's just all the world saves will be in the same file for all the accounts. If you saved all the worlds on that computer all the accounts will have access to all the worlds in there.If you have two computers with a new world saved on each one then you will not have access to each others world. If you accessed one account from a strange computer then you won't be able to access your world saves from your other computer.The worlds are saved to your computer, not the minecraft servers. You can still start another world but then when you get back to your other computer you won't be able to access that world.
You can't share a game between two accounts on steam, you'd have to buy the game again on the other account.
use different browser
Nope :P
use two different browsers like internet explorer and firefox
You can not log in two club penguin accounts at once on the same computer or laptop they have to be on a diffrent laptop or computer!So you cant actually log on two club penguin accounts on the same computer or laptop!Have to be on different ones!
You can't because your ip address (which is a unique number to your PC) will always stay the same... this is wrong hamachi has 3 seprate ip addresses on mine because it wont allow me to log on to my first one i started for minecraft. to do this just reinstall it and the ip will change..
Planet Minecraft and Minecraft Wiki are two sites i can think of.
I believe you can, even at the same time, but if you do a message pops up saying that you're logged in from another location. You can't, however, have 2 accounts playing on the one server.
Just like any computer it should...