[Asterisk-Users] same extension numbers ??

[justin]

Hi Guys

Im just wondering is it possible to setup the same extension number a few 
times. e.g say i have 2 seperate places using the same asterisk server.. is 
it possible for a user in each to have say extension 3333 ?
I tried setting up 2 users in diff contexts with the same username, it 
allowed me to do it, but once the first 3333 user was registered, when the 
2nd 3333 user registered he just replaced the first one. Is there anyway to 
allow both of them ?
Also while im emailing, i've had a look in parking.conf and tried heaps of 
diff settings etc and im wondering is it possible to setup multiple parking 
groups. e.g say theres 2 seperate companies using the server, you wouldnt 
realy want to share the parked calls ?
Is asterisk capable of 'virtual' servers or anything else which would be 
useful in running asterisk within 2 seperate organisations ??

thanks heaps for all your help :)

Justin