Question

Why there are person with similar face present on earth even though they r not any relative?

Answer 1

"There is only so much genetic diversity to go around," said Michael Sheehan, an assistant professor of neurobiology and behavior at Cornell University, who routinely studies appearance variations and genetics in species such as paper wasps and house mice. "If you shuffle that deck of cards so many times, at some point, you get the same hand dealt to you twice."

That said, that "deck of cards" is incredibly voluminous, Sheehan noted. Scientists currently have no idea how many genes play roles in establishing, for instance, the shape of human faces or the space between people's eyes.

There's a "huge number of genes that contribute to things like facial structure and, of course, hair, eye and skin color, which are all highly variable," said Dr. Arthur Beau det, a professor of molecular and human genetics at Baylor College of Medicine in Houston.

Evolution has seemed to favor a large degree of distinctiveness in human mugs. Sheehan and a colleague reported last year in the journal Nature Communications that human faces differ in their dimensions more than, say, hands vary in their widths and lengths. In addition, the scientists found that more genes are known to be linked to looks than to other areas of human anatomy.  

"Human faces are more variable than we would expect them to be based on how variable other body parts are," Sheehan said.

Answer 2

We all are related. Genetically. We all belong to the same gene pool.

Everybody on earth is at least 50th cousin with everybody else on the earth. Biologically, it is not so difficult to be almost identical.

If you go back just 65 generations (the time when Rome empire what building), you will require at least 1,000,000,000,000,000,000 people (I mean your parents, their parents, their parents, etc.) in all. This number is larger that the total number of human ever to be present on this planet. In fact larger that the total number of all of monkeys and primates together. This makes no sense. The only valid inference for this is that our ancestor were mostly practicing incest.

The further back in time you go, the lesser is the number of people. This suggests that there was a lot of incest. In fact there is a 1 in 5 chance that your neighbor(or your wife/date) and you were are from same family fewer than 10 generations ago.

There is no surprise as to why so many people look alike. In fact the picture you have posted are of famous people. There are other too. Lot of them. You may also be interested in the study that says everybody has a twin somewhere on this planet. 
They do say EVERYBODY has a twin: Mind-boggling portraits of unrelated look-alikes