I've come to learn that people will copy everything. I once built an iPhone app that seems to have topped out at around $500/year in income; barely enough to secure a developer for a day. Yet, I found two apps that I would consider clones of mine with many similar characteristics, not just someone trying to enter the same market.
I was quite flattered to see them, but I remain curious why they'd go after such small potatoes? It seems like copying something that has a sustainable business model would be the better choice.
If those two clones didn't exist, do you think your app would be collecting "their" revenue (i.e. $500/year * 2)? Maybe you three are splitting a small pie into smaller slices.
Probably not in any meaningful way. The clones never seemed to grab much traction in the rankings, where my app did. Though I guess I'll never know for sure. If anything, I'm losing out to the real competition that took their own approaches to solving the problem and didn't just clone what I did.
Out of curiosity, I just had a look at the ones I do consider clones, and the one that took my name and added "Pro" to the end doesn't even appear to be on sale anymore though their website is still active. I can't find the other, so it may not be either.
You can make some estimations by rankings, but I guess that's a fair question. Also, I spent several months on the project, so even a week of work per year isn't going to get you far.
