RCW 9.41.050 Section 1.(b) states the following, in part:
-http://apps.leg.wa.gov/RCW/default.aspx?cite=9.41.050Every licensee shall have his or her concealed pistol license in his or her immediate possession at all times that he or she is required by this section to have a concealed pistol license and shall display the same upon demand to any police officer or to any other person when and if required by law to do so.
Nowhere do I see it say a "copy", but it does say you have to have it... so I assume that it means you have to have the actual license. I would talk to a lawyer about that and get it in writing to carry copies of with you to hand to officers with the copy of the license.