This isn't a formula question, it's a VBA question. you would need a macro to parse out each string by the / delimiter and add it to a list if it's new. Here's a simple macro that can do this.... it assumes the data is in column A, it will create a new list for you in column D.
How/Where to install the macro:
1. Open up your workbook
2. Get into VB Editor (Press Alt+F11)
3. Insert a new module (Insert > Module)
4. Copy and Paste in your code (given above)
5. Get out of VBA (Press Alt+Q)
6. Save as a macro-enabled workbook
The macro is installed and ready to use. Press Alt-F8 and select it from the macro list.
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