2 Root Sites, 1 db

I know that the aspnet_applications table supports multiple apps but How can I have 2 root sites "/" setup to use seperate application IDs (users, etc).

I'm trying to limit the number of DBs I need to create on my server and reuse where I can. All my apps use seperate (specific) names for their tables so there is no overlap there.... I just want to reuse the aspnet_* tables (and provider stuff).

Thanks
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