I quote from Coincraft's Standard Catalogue for the Victorian Two Pound pieces:
"A large number of forgeries exist, especially of the 1887 coin. Many of these are of poor quality and 'wear' differently from genuine coins, especially around the head and breast of St. George. However many of these fakes are difficult to detect. Because of the prevalence of these 're strikes', as some dealers like to call them, it is probably advisable to look for coins in very fine condition, with a genuinely old appearance.
As with five pound pieces, care must be taken not to confuse proofs with early strikings. The rims and milling of genuine proofs should be examined whenever (you can), so that one becomes familiar with their appearance."