Thanks, my question was most inline with comments here about double spend.

Detecting double spend is easy as you said, but I am curious about the consequences.

Will this system will be somehow connected to real IDs? Who will in the network will have access to this data?

If so what is the process hiding my real ID from my identifier? I did shopping at the market, what will prevent them to see my all spending history?

If it is not connected to real ID somehow, what is preventing me to create a new identity?