If you look from an international perspective, there are companies started in Europe that did much better in the european markets than the "original" product. The end result is pretty much that the "original" had to buy out the clone.
Yes, but this is partly due to the (arguably) slow expansion of hot US startups into overseas markets. The Samwer brothers basically took an approach of copying successful US startups, so in some sense they can bootstrap some of the learning from the predecessor, while never having to directly compete (until the original decides to expand).
For example Groupon buying MyCityDeal
The Samwer brothers are experts at this http://www.wired.co.uk/magazine/archive/2012/04/features/ins...