I think that’s a little debatable.
I agree that it would be quite easy and convenient, since how contact is made isn’t very important, like @Cassady said.
However, situations do exist when one or both twins are already married. And, I believe that the number of people that are in commited relationships actively using dating apps is quite low. (though I could be wrong? 
)
Online in general would likely be a more realistic type of encounter in my opinion. Parricularly if both twins have shared interests.