Not sure if I'm understanding this correctly, but this could be misleading. As you add a dimension to a cube, it won't be possible to hook the same dimension in by two dates. Assuming you are using the same date dimension, it would hook in by the second date and becomes a role playing dimension. Let's say you have a dimension Date. It's hooked into the cube by the one date and then ideally renamed to the Geneva date (or whatever it is, I can't go back while I'm typing this reply). The dimension Date is then added again, hooking into the second date. It will also be renamed. There are some downsides to this, but generally role playing dimensions are the way to go. The main advantage is that any changes made to the Date dimension will automatically be a part of both dimensions in this case.