Date Attribution

Hello, new user here.  I've searched the web and have found bits and pieces of the answer to my question below, but nothing that helps drive me to a full solution.

We are operating in an EPBCS environment and need to load multiple date attributes to a custom dimension.  Think of this like a "Project" dimension, with StartDate, ReviewDate, EndDate, etc.

Option 1: I realize that we may need to tag our outline to allow duplicate member names to accomplish this.  Where is this setting located?

Option 2: We could prefix all dates (SD_01-01-17, ED_01-01-18, etc.) but would that not force a change to Text attribute type?  Would this then prohibit us from using these as true dates in calculations?