This is one of those areas of the WikiTree collaboration effort that is not easily solved.
When the page comes up listing the possible matches, there should also appear the Button allowing you to go ahead and create a new profile. The truth is, merging can be done later on.
It would be best never to create duplicate Profiles, but that is simply not a realistic notion in collaborative environment such as the WikiTree.
Thus, following the Honor Code, all we can really ask for and expect is that each contributor do the best they can to work within the framework while constantly challenging it to improve it - such as you are doing with this question.
AS far as rejecting the matches at that moment goes, that is what creating the new Profile really does. In effect, it rejects them all - at least temporarily.
Hope this helps,