Regarding the posts with the same title ... you don't actually need to create a unique post title for each post. Just make sure the SLUG is unique. So you can have 100 posts all named "Weekly Update", but the slug should be weekly-update-1,
If you ensure each slug is unique, then you don't actually need to upgrade to 126.96.36.199. If you do want to upgrade to 188.8.131.52, here's some instructions ....
If you download the any of the latest builds on the Source Code tab, you'll first need to compile the BE core using Visual Studio. This will produce a BlogEngine.Core.DLL file that you'll want in your BIN folder.
You can keep all your posts. I would first make a backup of everything you have, just in case something doesn't work. Then overwrite your folder/files with the folder/files from BE 184.108.40.206. EXCEPT, don't overwrite the App_Data folder.
That's where all your data is (assuming you're not using the DB for storage). If you've made any changes to the web.config file, you will want to avoid overwriting that too.
You'll next want to reapply any changes you made to CommentView and other files to the 220.127.116.11 files.
One folder you'll no longer need is the ExtensionsManager folder under App_Code. This code has been moved into the BE core. So you will need to delete the ExtensionsManager folder under App_Code.
If you're using widgets, you'll probably need to update your theme's CSS file since there's a minor breaking change to accommodate multiple widget zones. I describe the impact of the changes
That's all that comes to mind now, in terms of changes. But as long as you have that "just in case" backup, you'll be in a good shape.