Experiment with CuCl2.2H2O, HCl and copper

An experiment was done with copper chloride and copper, showing formation of a dark brown complex. What is this dark brown complex?

The experiment is performed as follows:

Put a small amount of CuCl2.2H2O in a testtube and set aside a small amount of copper wire:

Add some HCl (30%) to the testtube and shake a while, until all copper chloride is dissolved. The liquid now is green/yellow:

Finally add the small piece of copper and shake for a few minutes. After a few minutes the result is as follows:

The liquid has become much darker.

Question now is: what is the dark compound? The dark compound cannot simply be a compound of copper (II). Addition of copper, results in formation of copper (I). Is the dark color due to formation of a copper (I)/ copper (II) complex?