When we are doing directory submission, can we submit our web site in same sites(like site having diff domain but the structure link all the thinks are same, only difference is there domain name). so is it helpful to submit our website link in those sites. please reply me thanks
Of course you can do it but not so much good as you will submit to a new directory which is hosted on different IP.
It can be useful but it's somewhat doubtful. There are lots of .info directories with the same template/ links. You might find that the directories don't last too long and the domain expires even if you do get listed.
Design does not matter. You should check IP and contents, if that is different then there should not be any problem.
It's pretty much pointless to post a duplicate link in a duplicate directory, because chances are that content is not going to be "duplicated" in the SE. One may be indexed, but the rest will not be, or will be severely penalized. Beware of carbon copy directory sites. If it looks just like another one, chances are, its just an off the shelf copy - content included.