Site changing URL structure

Hi

When i go to add new posts to my site it is changing the URL structure as if it has that domain already.

Example.

I add a post to my site which is http://www.stepbybet.com

This is a typical URL structure that I want

http://www.stepbybet.com/open-account/bet365/

But when I add another post under a different category but same end of URL it changes it to -2 (or however many pages there are with the same ending. E.G.

http://www.stepbybet.com/place-a-bet/bet365-2/

Where I would want that to be:

http://www.stepbybet.com/place-a-bet/bet365/

Hopefully that makes sense.

I don’t have any posts that are drafts or that are in the trash to contradict it to thinking that there are multiple posts the same.

Any help would be massively appreciated.