Occasionally, you and a colleague will both make changes to the same text in the same topic at the same time. This will only happen if you really both edit the same sentence in different ways. Changes in different locations in the same project or even the same topic will be merged silently by SVN, but may still create contradictions in the meaning of your text, so you really always need to coordinate with colleagues before working on the same topics.
When conflicts occur, you need to be able to see your version of the text and the conflicting version and choose which one you want to save to the repository. This is done in a "merge tool", which shows you the versions side by side. Unfortunately, even though Tortoise SVN is an outstanding SVN client, its merge tool is not intuitive enough for normal users working in a program like Help+Manual.
Use WinMerge or Beyond Compare
There are two solutions we can recommend: The free WinMerge tool or the paid Beyond Compare tool in the Pro version. Both are excellent, and it is really up to you which one you use.