Which of these coins are legal to own?

Both! 

And both are counterfeit. 

The reason they are legal to own is both have been properly countermarked with the word COPY in compliance with the Hobby Protection Act (Public Law 93-167). COPY can be stamped on either side of the counterfeit coin but must be in size relationship to the diameter of the coin. The specific COPY sizes are prescribed by the Hobby Protection Act.

Unless counterfeit coins are marked with COPY, they are illegal to possess, import, buy or sell in the United States. (US Code: Title 18, Part I, Chapter 25, Sections 485 through 492.) Conviction of the pertinent federal laws can subject one to hefty fines and up to 20 years in federal prison.