The events where 'd' has a meaning are the 3xxxx parameterized events. AFAIK for the 1xxxx events the d is not used, i.e. there can be only one per user. 

If we wanted mutiple lists it should be a 3xxxx number. 

But it might be ok to just have one profile gallery list. 

 So maybe have both, a 10011 profile gallery and a 30xxx gallery sets  

 Yes, I think it's a different use case.  

 Yes, I think it's a different use case.  

 Got rid of the dtag, you're right.