Ability to associate two issue types with one project & need different prefix for both types

1. For every project we have issues opened in-house by our development team during the production and testing process
called "Issues" and we have our customers opening issues for the same Project for the modules that are already in Production which are called Incidents. The customers do not have access to our internal issues. With our current defect tracking system, we have the ability to separate the two per project. But now we are stumped and consider this a Show-stopper as we will either have to have 2 different Projects - one for the customers and one for Internal use. We consdider this a lot of hassle and duplication of effort.
2. The issues and Incidents need to have separate Key to differentiate them.