[Culhwch]

I'm a little confused by your post title and post content, and the responses... Do you mean that you have one project for which you originally had planned one ending, but were suddenly struck with another possible - albeit less solid - ending (ie 'two endings')? Or do you have one project that you've lost enthusiasm for now that another completely unrelated idea for a second project has popped up? I assumed the former, but everyone else seems to have answered the latter.

If it is the first, then I'd say explore the new idea, and see what comes of it. If it doesn't work out, you can always go back to the first ending, or a third ending may present itself to you.

Remember, in writing there is no one right way. Explore, create, discover.

EDIT: I've also moved this out of Writing Resources and into Aspiring Writers, as it's not really a resource, only a discussion...