Listing article updates on cv
Let me assume that you already have listed in your CV the earlier article (the version 1) in the following way.


  Author Name, Title, Encyclopedia, Version 1, Dated online: xx-xx-xxxx; WWW: website


Now, you could just replace the above with the following:


  Author Name, Title, Encyclopedia, Version 2, Dated online: xx-xx-xxxx; WWW: website (Web version 1: website)


Though there is 25% difference, I would not go with redundant information in a CV.