Hi rosana a solution to that would be to extend a little the second video clip, and convert it into a composite clip to which you then add that transition, so that what is played in the middle of the transition is irrelevant, let me know if you have understood correctly or if you have any doubts about how to do that.
-the part of the second video clip you can extend it in several ways, one of them would be, freeze the first frame extend it as much as you need, and then join that frozen frame with the real beginning of the video clip in a composite clip to which you will then add that transition effect together with the other video.