Ooh cool... so it's basicly a restrike, or overstrike like they do with dates pretty often?!
The technical term is an "overstrike", not a "restrike", but it's not the same as what they "do with dates pretty often" - that's what's known as an overdate. The words are similar but the causes are completely different. An overdate is where the die
with an old date is edited to carve a new date onto it; overdated coins were struck only the once from a blank planchet, not an older coin. An overstrike is where the coin
is struck once, then sometime later is struck a second time using a completely different pair of dies.
Other series that are famous for overstrikes are Bank of England 1804 dollars and Brazilian 960 reis of the early 1800s. As a general rule, if the original coin or "undertype" is fully identifiable, it does add a little extra value than if only random unidentified remnants of the older coin are visible. In this case, the "4" from 1894 is readily apparent in your pics, below the "old 9" inside the colour-hatching on the shield, so I'd class yours as identifiable. Here's what the 1894-5 20c looks like
. I have a 1919 20c but there's only a faint hint of the old "20" on the reverse. Not identifiable.
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