Error Sovereign
 

A guy I used to work with showed me a 1925 George IV Sovereign that he said is an error coin. The dealer he got it from had a specific name for the type of error but the guy can't remember what it was. He said the dealer told him that the dies had struck together without a coin present and impressed themselves.

The coin shows some lightly struck reverse details on it's obverse, and some lightly struck obverse detail on the reverse.

Does this coin have any collectors value, and if so does anyone know what the coin is worth above gold content plus maybe a 3 dollar premium?