For all intents and purposes, the original Double Shot is identical to the much more mass produced Orange and Green version, with the major difference being the coloring. It primes and fires in the same way, shells eject after the back opens and the stock opens up to store up to 4 shells. I did find this particular Double Shot lacking in range, only achieving about 10' ranges. I'm not sure if the original generally had poor performance or if this one is just old, but my research indicates the latter.
While there is no benefit per say for the older model over the newer colors (the other side-by-side, not the over-under), I personally think it looks better.