Hello and welcome. 
If you have a "silver two pence coin", the most likely explanation for it is that it has been plated. People plate coins for all sorts of reasons. Some people would plate 2 pence coins and hope to pass them for 10 pence (which were about the same size). Doing this is, of course, illegal.
To make any kind of assessment about your coin, we will need:
- Clear photos of your actual coin
- An accurate weight, in grams to at least two decimal places. If it weighs about 7.12 grams, then it's almost certainly not a "wrong planchet" error.
Actual mint errors, where the Mint has used the wrong metal or a wrong planchet, are possible but extremely rare (which is why they are valuable).
Because these genuine mint errors are so rare, there is no "fixed price" or "catalogue value" for them - they are worth whatever people on the day are prepared to pay.

If you have a "silver two pence coin", the most likely explanation for it is that it has been plated. People plate coins for all sorts of reasons. Some people would plate 2 pence coins and hope to pass them for 10 pence (which were about the same size). Doing this is, of course, illegal.
To make any kind of assessment about your coin, we will need:
- Clear photos of your actual coin
- An accurate weight, in grams to at least two decimal places. If it weighs about 7.12 grams, then it's almost certainly not a "wrong planchet" error.
Actual mint errors, where the Mint has used the wrong metal or a wrong planchet, are possible but extremely rare (which is why they are valuable).
Because these genuine mint errors are so rare, there is no "fixed price" or "catalogue value" for them - they are worth whatever people on the day are prepared to pay.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis